Merge branch 'development' into feature/portal-ledger-support

* development: (437 commits)
  Publish
  Update yarn.lock
  Update the CHANGELOG
  Fix the bug making it impossible to specify the custom ZRX address
  Fix fill/cancel order by looking for NoError instead of empty blockchainErr given the BlockchainErrs type refactor
  Add a comment about a yarn bug
  Add our mainnet and kovan nodes as backups for Portal requests
  Fix bug hiding the user info from topBar
  Add dev-utils package to top level README
  Prettier newline
  Prettier
  Allow Token symbols to be alphanumeric
  Update CHANGELOG, rebase on development
  Should not -> cannot
  Reject negative amounts in isValidBaseUnitAmount
  Re-add changelog for 0x.js
  Fix prettier
  Update yarn.lock
  Move tests to a separate folder
  Change file layout
  ...

# Conflicts:
#	packages/website/README.md

6 files changed, 108 insertions, 9 deletions

diff --git a/packages/utils/src/address_utils.ts b/packages/utils/src/address_utils.ts
new file mode 100644
index 000000000..f94985441
--- /dev/null
+++ b/packages/utils/src/address_utils.ts
@@ -0,0 +1,36 @@
+import * as jsSHA3 from 'js-sha3';
+
+const BASIC_ADDRESS_REGEX = /^(0x)?[0-9a-f]{40}$/i;
+const SAME_CASE_ADDRESS_REGEX = /^(0x)?([0-9a-f]{40}|[0-9A-F]{40})$/;
+
+export const addressUtils = {
+    isChecksumAddress(address: string): boolean {
+        // Check each case
+        const unprefixedAddress = address.replace('0x', '');
+        const addressHash = jsSHA3.keccak256(unprefixedAddress.toLowerCase());
+
+        for (let i = 0; i < 40; i++) {
+            // The nth letter should be uppercase if the nth digit of casemap is 1
+            if (
+                (parseInt(addressHash[i], 16) > 7 && unprefixedAddress[i].toUpperCase() !== unprefixedAddress[i]) ||
+                (parseInt(addressHash[i], 16) <= 7 && unprefixedAddress[i].toLowerCase() !== unprefixedAddress[i])
+            ) {
+                return false;
+            }
+        }
+        return true;
+    },
+    isAddress(address: string): boolean {
+        if (!BASIC_ADDRESS_REGEX.test(address)) {
+            // Check if it has the basic requirements of an address
+            return false;
+        } else if (SAME_CASE_ADDRESS_REGEX.test(address)) {
+            // If it's all small caps or all all caps, return true
+            return true;
+        } else {
+            // Otherwise check each case
+            const isValidChecksummedAddress = addressUtils.isChecksumAddress(address);
+            return isValidChecksummedAddress;
+        }
+    },
+};
diff --git a/packages/utils/src/class_utils.ts b/packages/utils/src/class_utils.ts
new file mode 100644
index 000000000..04e60ee57
--- /dev/null
+++ b/packages/utils/src/class_utils.ts
@@ -0,0 +1,18 @@
+import * as _ from 'lodash';
+
+export const classUtils = {
+    // This is useful for classes that have nested methods. Nested methods don't get bound out of the box.
+    bindAll(self: any, exclude: string[] = ['contructor'], thisArg?: any): void {
+        for (const key of Object.getOwnPropertyNames(self)) {
+            const val = self[key];
+            if (!_.includes(exclude, key)) {
+                if (_.isFunction(val)) {
+                    self[key] = val.bind(thisArg || self);
+                } else if (_.isObject(val)) {
+                    classUtils.bindAll(val, exclude, self);
+                }
+            }
+        }
+        return self;
+    },
+};
diff --git a/packages/utils/src/configured_bignumber.ts b/packages/utils/src/configured_bignumber.ts
new file mode 100644
index 000000000..e44c062c2
--- /dev/null
+++ b/packages/utils/src/configured_bignumber.ts
@@ -0,0 +1,9 @@
+import { BigNumber } from 'bignumber.js';
+
+// By default BigNumber's `toString` method converts to exponential notation if the value has
+// more then 20 digits. We want to avoid this behavior, so we set EXPONENTIAL_AT to a high number
+BigNumber.config({
+    EXPONENTIAL_AT: 1000,
+});
+
+export { BigNumber };
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index a61f04ad2..2768e49ab 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -1 +1,5 @@
-export {promisify} from './promisify';
+export { promisify } from './promisify';
+export { addressUtils } from './address_utils';
+export { classUtils } from './class_utils';
+export { intervalUtils } from './interval_utils';
+export { BigNumber } from './configured_bignumber';
diff --git a/packages/utils/src/interval_utils.ts b/packages/utils/src/interval_utils.ts
new file mode 100644
index 000000000..ebecc7015
--- /dev/null
+++ b/packages/utils/src/interval_utils.ts
@@ -0,0 +1,37 @@
+import * as _ from 'lodash';
+
+export const intervalUtils = {
+    setAsyncExcludingInterval(fn: () => Promise<void>, intervalMs: number, onError: (err: Error) => void) {
+        let locked = false;
+        const intervalId = setInterval(async () => {
+            if (locked) {
+                return;
+            } else {
+                locked = true;
+                try {
+                    await fn();
+                } catch (err) {
+                    onError(err);
+                }
+                locked = false;
+            }
+        }, intervalMs);
+        return intervalId;
+    },
+    clearAsyncExcludingInterval(intervalId: NodeJS.Timer): void {
+        clearInterval(intervalId);
+    },
+    setInterval(fn: () => void, intervalMs: number, onError: (err: Error) => void) {
+        const intervalId = setInterval(() => {
+            try {
+                fn();
+            } catch (err) {
+                onError(err);
+            }
+        }, intervalMs);
+        return intervalId;
+    },
+    clearInterval(intervalId: NodeJS.Timer): void {
+        clearInterval(intervalId);
+    },
+};
diff --git a/packages/utils/src/promisify.ts b/packages/utils/src/promisify.ts
index c114cf32f..29d626b61 100644
--- a/packages/utils/src/promisify.ts
+++ b/packages/utils/src/promisify.ts
@@ -5,16 +5,11 @@ import * as _ from 'lodash';
  * Promisify provides a default callback of the form (error, result) and rejects when `error` is not null. You can also
  * supply thisArg object as the second argument which will be passed to `apply`.
  */
-export function promisify<T>(
-    originalFn: (
-        ...args: any[],
-        // HACK: This can't be properly typed without variadic kinds https://github.com/Microsoft/TypeScript/issues/5453
-    ) => void,
-    thisArg?: any,
-): (...callArgs: any[]) => Promise<T> {
+// HACK: This can't be properly typed without variadic kinds https://github.com/Microsoft/TypeScript/issues/5453
+export function promisify<T>(originalFn: (...args: any[]) => void, thisArg?: any): (...callArgs: any[]) => Promise<T> {
     const promisifiedFunction = async (...callArgs: any[]): Promise<T> => {
         return new Promise<T>((resolve, reject) => {
-            const callback = (err: Error|null, data?: T) => {
+            const callback = (err: Error | null, data?: T) => {
                 _.isNull(err) ? resolve(data) : reject(err);
             };
             originalFn.apply(thisArg, [...callArgs, callback]);