Rewrote XWiki backed storage to work with new API.

Stores documents and attachments, attachments accept and return Blob type.
Tests are run with mocks and if the URL containt /xwiki/bin/ then they are run on the live wiki
    (user must be logged in for them to pass).

test/jiotests_withoutrequirejs.html

@@ -33,6 +33,8 @@
   </script>
   <script type="text/javascript" src="../complex_queries.js"></script>
   </script>
+  <script type="text/javascript" src="../src/jio.storage/xwikistorage.js">
+  </script>
   <script type="text/javascript" src="./jiotests.js"></script>
 </body>
 </html>