Reimplements ProxyTicket and ProxyGrantingTicket

Includes logic to handle associations
Reimplements ServiceTicket and renamespaces SingleSignOutNotifier
Reimplements TicketGrantingTicket
Reimplements User
Reimplements TwoFactorAuthenticator
Reimplements ServiceRule
Restricts SSO Notifications in test mode

This prevents having to constantly stub out logic that falls outside of
the scope of the object under test.
Refactors Ticket Validator tests from dynamically created to using Shared Examples
Reimplements ValidationResult
Removes the Model namespace
Deprecates the db/ folder

* Removes checked-in development SQLite DB
* Removes migrations (will be moved to CASino)
* Removes schema.rb
Moves "add service rule" rake task to ServiceRule#add

Doing so makes this non-trivial logic testable