Convert participation app to django model

[Kirska]

Convert the participation app fields to a django model:
participant_app_table.txt

Only field names and types needed. Id and color can be ignored.

Do not add fields to this table that will exist on the Pets table or Persons table. The pets table schema can be found on #2. We will create a link to the pet and person table when an app is submitted. Person table will just be very basic contact info: name, address, phone, etc.