This is a work in progress commit and all storages are broken.

* Use as much as possible RSVP promise to simplify the code.
* simplify error management: use Error class in case of problem.
* Drop the job management at that point. Such functionnality could be reimplemented as a storage.
* Start to simplify the tests, to speed up debugging.
* Drop requireJS usage, as the goal for now is to make it usage on browser.
* allDocs has to be rewritten to ease storage tree capacity checking. A storage should only implement what it could really do.
* disable attachment management for now.