Traceback when removing a account

[misc]

After adding a fresh account ( called test ), and removing it from gajim ( and not from server ), gajim show the following backtrace :

Traceback (most recent call last):
  File "/home/misc/checkout/svn/gajim/src/common/xmpp/idlequeue.py", line 136, in process_events
    obj.pollout()
  File "/home/misc/checkout/svn/gajim/src/common/xmpp/transports_nb.py", line 351, in pollout
    return self._do_send()
  File "/home/misc/checkout/svn/gajim/src/common/xmpp/transports_nb.py", line 523, in _do_send
    self.disconnect()
  File "/home/misc/checkout/svn/gajim/src/common/xmpp/transports_nb.py", line 396, in disconnect
    self.on_disconnect()
  File "/home/misc/checkout/svn/gajim/src/common/connection.py", line 794, in _on_disconnected
    self.dispatch('STATUS', 'offline')
  File "/home/misc/checkout/svn/gajim/src/common/connection.py", line 157, in dispatch
    self.put_event((event, data))
  File "/home/misc/checkout/svn/gajim/src/common/connection.py", line 153, in put_event
    gajim.handlers[ev[0]](self.name, ev[1])
  File "gajim.py", line 486, in handle_event_status
    self.minimized_controls[account].values():
KeyError: u'test'

[asterix]

(In [8339]) fix TB when we remove an account. Fixes #3268