Improve user feedback on the Profile > Design page

- Header changes immediately without a page reload
- Lets the user know that we actually saved their setting when changed

app/assets/javascripts/profile.js.coffee

@@ -0,0 +1,10 @@
+$ ->
+  $('.edit_user .application-theme input, .edit_user .code-preview-theme input').click ->
+    # Hide any previous submission feedback
+    $('.edit_user .update-feedback').hide()
+
+    # Submit the form
+    $('.edit_user').submit()
+
+    # Go up the hierarchy and show the corresponding submission feedback element
+    $(@).closest('fieldset').find('.update-feedback').show('highlight', {color: '#DFF0D8'}, 500)