handleParticipation method

Future<Null> handleParticipation ()

Handles the participation to the party, updating the catalogue (adding the number of stuff that the participant is going to bring). TODO: In the future it will even handle the participants' profiles.

Implementation 

Future<Null> handleParticipation() async {
  print('Handling participation');
  Party party = await _getPartyFromFirestore(id);
  print('\nIn handleParticipation the local catalogue is:');
  catalogue.printCatalogue();
  party.catalogue.update(catalogue);
  print('\nAfter update:');
  party.catalogue.printCatalogue();
  await party._updateParty();
  print('Done, theoretically');
}