update presence when account is enabled
update presence when account is enabled

the problem was that disabling accounts forced their requested presence to _offline_, when the account was re-enabled the r-s stayed offline and the account did not try to reconnect. this was introduced with TpAccount. fixes bug #602821

GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets