veyron-browser: Upgrading Polymer to the lastest verion and fixing
breaking changes. Also since Polymer now has a spinner component
removing our custom paper-loading web component and using paper-spinner
instead.

Change-Id: I97568ea293d495fce46da878870d79b8bfa58ce9
diff --git a/bower.json b/bower.json
index e8ac722..a322029 100644
--- a/bower.json
+++ b/bower.json
@@ -1,8 +1,8 @@
 {
   "name": "veyron-browser",
   "dependencies": {
-    "polymer": "Polymer/polymer#~0.4.0",
-    "core-elements": "Polymer/core-elements#~0.4.0",
-    "paper-elements": "Polymer/paper-elements#~0.4.0"
+    "polymer": "Polymer/polymer#~0.5.1",
+    "core-elements": "Polymer/core-elements#~0.5.1",
+    "paper-elements": "Polymer/paper-elements#~0.5.1"
   }
 }