Fixed es.json (#354)

* Fixed es.json
- converted remaining english to spanish in file so as to check more locations.
- the `formatjs compile` for Spanish was failing converted back to english for now. build does the correct thing, so it's more just to keep things correct in source.
* add support for eslint-plugin-formatjs
 - eslint rules for formatjs
 - we are mostly protected by typescript checking, but this is a nice sanity check.

client/.eslintrc.js

@@ -20,9 +20,11 @@ module.exports = {
   'plugins': [
     'react',
     '@typescript-eslint',
+    'formatjs',
   ],
   'rules': {
     'max-len': [2, {'code': 120, 'tabWidth': 4, 'ignoreUrls': true}],
+    'formatjs/no-offset': 'error',
   },
   'settings': {
     'react': {