move non-app assets to vendor

app/assets/javascripts/application.js

@@ -10,6 +10,8 @@
 //= require jquery.ui.selectmenu
 //= require jquery.tagify
 //= require jquery.cookie
+//= require modernizr
+//= require chosen
 //= require raphael
 //= require branch-graph
 //= require_tree .

app/assets/stylesheets/application.css

@@ -5,6 +5,7 @@
  *= require jquery-ui/jquery-ui
  *= require jquery-ui/jquery.ui.selectmenu
  *= require jquery-ui/jquery.tagify
+ *= require chosen
  *= require_self
  *= require_tree .
 */