Change ESLint quote-props rule to as-needed

Also fixes all files flagged by the rule

common/models/user.js

@@ -44,7 +44,7 @@ module.exports = function(User) {
 
   // username should not be in blacklist
   User.validatesExclusionOf('username', {
-    'in': blacklistedUsernames,
+    in: blacklistedUsernames,
     message: 'is taken'
   });