Adding 2 columns to the event roster export "is_paid" and "primary_registrant"
Refactoring the event roster export

Using Registration.registrant attribute that already exists to access primary registrant.
PEP8 memberships/models and memberships/views
Updated Invoice.bill_to and Invoice.ship_to method

These methods assumed that the User.profile attribute exited, now we check before referencing the profile attribute.
Updating the membership application

When adding a member through the membership application we now check if old memberships have a user.profile attribute.  If the attribute and relationship does not exist, we create it.