Match the cancel orange to the color palette.
Replace attendance screen with an index screen (#14).

- The attendance screen is unnecessary (use attendees).
- Remove the template for the Attendance view.
- Modify controller prev/next logic to use index instead of attendance.
- Add index template.
- Update router to transition fluidly withoutn needing beforeModel.
Remove view reliance on Reservation isAttending* properties.
Remove isAttending* properties on Reservation (#14).

The Contacts table/object will store this state and
it will be computed as needed. There is no reason to
have it on a separate object and screen when it depends
on the Contacts.

- Remove all references to isAttendingBigDay on Reservation object.
- Rmeove all references to isAttendingRehearsalDinner on Reservation object.
Continue work on refactoring out isAttending* (#14).

- Remove all properties using it and reuse.
- Remove any excess code that is not needed.
- Refactor some properties into the baseController.
Finish refactor of RSVP Screens (#14).
> Merge branch 'rsvp-screens-update' into development