Added PurpleAccountUiOps callbacks. (Updated)

Added PurpleAccountUiOps callbacks. (Updated)

FIXES:
 - Added missing structures on account.pxd (PurpleAccountUiOps) and status.pxd (PurpleStatus).
 - Added account callbacks forwarding on purple.pyx.
 - Added account callbacks example on nullclient.py.
 - Added c-based callbacks on account_cbs.pxd.
 - Renamed conversations_cbs to conversation_cbs.

ps: Fixed typo when renaming conversations_cbs to conversation_cbs.

Signed-off-by: Bruno Abinader <bruno.abinader@indt.org.br>

git-svn-id: https://garage.maemo.org/svn/carman/branches/carman-0.7-beta2/python-purple@1303 596f6dd7-e928-0410-a184-9e12fd12cf7e