PERF: add one more asset for ember and jQuery

at the moment Ember initialization is a bottleneck, to minimize impact
on initial load we download an evaluate it as early as possible

app/assets/javascripts/ember_jquery.js

@@ -0,0 +1,2 @@
+//= require jquery_include.js
+//= require ember_include.js

app/assets/javascripts/vendor.js

@@ -3,8 +3,6 @@
 //= require probes.js
 
 //= require handlebars.js
-//= require jquery_include.js
-//= require ember_include.js
 //= require i18n-patches
 
 //= require loader

app/views/layouts/application.html.erb

@@ -20,6 +20,7 @@
 
     <%= script "preload_store" %>
     <%= script "locales/#{I18n.locale}" %>
+    <%= script "ember_jquery" %>
     <%= script "vendor" %>
     <%= script "application" %>
     <%- if staff? %>