clean-up of models.py for pep8 compliance
clean-up of models.py for pep8 compliance

eosrei/roundware-server,probabble/roundware-server,jslootbeek/roundware-server,Karlamon/roundware-server,jslootbeek/roundware-server,yangjackascd/roundware-server,probabble/roundware-server,jslootbeek/roundware-server,yangjackascd/roundware-server,Karlamon/roundware-server,IMAmuseum/roundware-server,IMAmuseum/roundware-server,IMAmuseum/roundware-server,eosrei/roundware-server,probabble/roundware-server,jslootbeek/roundware-server,yangjackascd/roundware-server,Karlamon/roundware-server,Karlamon/roundware-server,probabble/roundware-server,eosrei/roundware-server,IMAmuseum/roundware-server,eosrei/roundware-server,yangjackascd/roundware-server