VMM{,/cli}/Handler: adjusted user* methods to the changes in Account.
All user methods was renamed from userAction() to user_action().
Added missing docstrings.
VMM/Account: some modifications and small improvements in class Account.
- replaced the tid by a Transport instance
- check mailbox format dependencies in _repare()
- reset all attributes when the Account was deleted
- don't select information, we have already, from the db
- added __nonzero__() method