[fixup] Small tweak to previous ActiveSupport::Configurable
Upgrades RSpec to latest release
Consolidates custom exceptions into a single location

* CASinoCore::Error for all CASinoCore related errors to inherit from.
  Similar in concept to Ruby's StandardError, this allows users to
  rescue from any type of CASinoCore error that may be raised
* Renames ServiceNotAllowedError to ServiceNotAllowed to be more
  consistent
* Adds MissingImplementor with a custom initializer to make raising
  easier
Removes database-specific Rake tasks
Simplifies the loading of Rake tasks
Removes ActiveRecord connection establishment

Since this is not core CAS-logic, this should be handled by the host
application.
[wip] first stab at orm-agnosticism
[wip]
[wip] LT tests pass
[LT fu] don't obfuscate the AM finder interface
Reimplements ProxyTicket and ProxyGrantingTicket

Includes logic to handle associations