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
.. Substitutions in section 1
.. |account.disk_usage| replace:: `account.disk_usage`
.. _account.disk_usage: vmm.cfg.5#account-disk-usage
.. |domain.force_deletion| replace:: `domain.force_deletion`
.. _domain.force_deletion: vmm.cfg.5#domain-force-deletion
.. |misc.transport| replace:: `misc.transport`
.. _misc.transport: vmm.cfg.5#misc-transport
.. #EOF