Handle cases when for gadget_data_source and gadget_data_handler we have
empty strings.

loaded. Add simple test.

"data-" prefix.

RenderJS.

On Google Chrome or Chromium, requests methods (POST,PUT,GET,DELETE) act on the
internal browser cache, so important action like PUT could not work.
The Url sended with the request is appended by '?_=xxx' (which 'xxx' is the
current date in ms) to make this Url unique.

Redesigned to use put,get,remove and allDocs instead of
{save,load,remove}Document and getDocumentList.
These methods are similar to PouchDB methods.
Error objects are similar to jQuery and CouchDB.
Error status are unique.
Storage design difficulty decreased.

elrte new document is now empty.
We can now remember previous JSON login.

SlickGrid can now show documents that are in conflict or not,
and Basic Conflict Manager shows the last modify date of revisions.

It returns now an object containing the new revision instead of the new revision only

GetDocumentList from conflict or dav with no document never calls fail or done