Bump version to 0.91
Remove worker threads from media renderer api implementation.

This causes random crash while starting up. Now on create the manager
on the main loop directly.

BUG=XWALK-2276
Merge pull request #366 from sragavan/xwalk-2276

Remove worker threads from media renderer api implementation.
Bump version to 0.92
Multi user features :

->Use Usr App related fonctions instead of Global App related Functions

Signed-off-by: Sabera Djelti (sdi2) <sabera.djelti@open.eurogiciel.org>