Improve 'hidden fields from hash' helpers
Create forms/_has_many_associations shared partial
Install 'better_errors' gem
bundle update (with some cleanup)
Comment out 'debugger' gem
Associate TicketBook with Membership (1st commit)

Basic chenges to associate TicketBook with Membership instead of MembershipType, and to nest TicketBooksController under MembershipsController.

Made the tests pass.
WIP
WIP