Multiple frontend support (#110)

* Initial multiple frontend support

* Removed unnecessary require()

* Moved styles/images out of common

config/initializers/frontends.rb

@@ -0,0 +1,7 @@
+# Be sure to restart your server when you modify this file.
+
+Rails.application.configure do
+  frontends = []
+  Rails.root.join('app', 'javascript', 'packs', 'frontends').each_child(false) { |f| frontends.push f.to_s }
+  config.x.available_frontends = frontends
+end