Lint `.json` files (#6852)

We've been using the `eslint-plugin-json` plugin for some time, but we
haven't been visiting `.json` files in the lint script. The lint script
has now been updated to incude `.json` files, which means any invalid
JSON will result in a lint error.

Unfortunately this JSON plugin doesn't seem to apply the other eslint
rules (such as `key-spacing`) to the JSON files. I wasn't able to find a
way to get that to work. Instead I manually auto-formatted each of the
locale `message.json` files, which fixed many whitespace
inconsistencies.

The `states.json` file was deleted completely, as it appears to be
unused. It wasn't a valid JSON file anyway, it was JavaScript. It looks
like a `states.js` file is automatically generated, but an old copy was
accidentally saved as `states.json` and included in the repo.

Many duplicate key errors were found and fixed in the
`development/states/` JSON files.

`package-lock.json` was added to `.eslintignore` because it was very
slow to lint, and linting it doesn't provide much value.

1 files changed, 1 insertions, 2 deletions

diff --git a/development/states/personal-sign.json b/development/states/personal-sign.json
index 8ded6205c..f1941a19c 100644
--- a/development/states/personal-sign.json
+++ b/development/states/personal-sign.json
@@ -18,7 +18,6 @@
       }
     },
     "unapprovedTxs": {},
-    "currentCurrency": "USD",
     "conversionRate": 13.2126613,
     "conversionDate": 1487888522,
     "noActiveNotices": true,
@@ -96,4 +95,4 @@
     "warning": null
   },
   "identities": {}
-}
\ No newline at end of file
+}