Behaviour to do authorisation checks for events.
RBAC for BaseEventTypeController.
RBAC for remaining core controllers.
Support for getting and setting roles in User model.
Role assignment in user admin tool.
Tidy up default access rules.

 * Default deny in BaseController, no need for default admin allow as everything now goes through RBAC
 * Default allow for admin in AuthManager
Remove obsolete methods.
Remove access_level and remaining references to it.