Dropped no longer used and disabled test.
Dropped not used IContactInformation.get_clients method.
Actor: add missing `corresponds_to` property for main implementation.
LocalRoleSetter: Replaced self-made responsible getter and use actor instead.

Additionally I've dropped the no longer used `IContactInformation.get_groupid_of_inbox` method.
Dropped no longer used `IContactInformation.get_client_of_inbox`.
Removed not used imports and helper methods.