Add language detection (#1772)

* Add language detection via WhatLanguage and (de)serialization of it through Atom

* Fix default language in ProcessFeedService

* Re-add newline before 'react-rails' Gem to fix groupings

Fixes Code Climate issue

Gemfile.lock

@@ -455,6 +455,7 @@ GEM
     websocket-driver (0.6.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.2)
+    whatlanguage (1.0.6)
     xpath (2.0.0)
       nokogiri (~> 1.3)
 
@@ -541,6 +542,7 @@ DEPENDENCIES
   tzinfo-data
   uglifier (>= 1.3.0)
   webmock
+  whatlanguage
 
 RUBY VERSION
    ruby 2.4.1p111