More fixes on purple.pyx.

FIXES:
 - accounts dict is now private.
 - load_accounts is now called inside purple_init.
 - Internal PurpleAccount data is now caught using libpurple functions.
 - Fixed some logic in account_add and account_verify.
 - Updated changes on nullclient.py and nullclient-ecore.py.

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@1356 596f6dd7-e928-0410-a184-9e12fd12cf7e