BoundLog eq implemented

useful when testing different mock_log objects bound with same args
FakeSupervisor for easier testing - inspired from @radix
working delete server implementation

- delete endpoint is now "DELETE ../groupId/servers/serverId" instead of
"POST ../groupId/delete_server".
- Not implementing GET on ../servers/ and servers/serverId
- moved remove_server_from_group from controller to supervisor
- tests added for rest and supervisor changes