Remove Recurring Event Concept

[jrjohnson]

Remove all entities, manger, controllers etc for RecurringEvent. Creating recurring events will still be supported in the front-end, but the recurrence will not be persisted to the DB.

[stopfstedt]

$ egrep -irl 'recurring_event|recurringevent' src/
src/Ilios/AuthenticationBundle/Voter/RecurringEventVoter.php
src/Ilios/AuthenticationBundle/Resources/config/voters.yml
src/Ilios/CoreBundle/Handler/RecurringEventHandler.php
src/Ilios/CoreBundle/Entity/OfferingInterface.php
src/Ilios/CoreBundle/Entity/Manager/RecurringEventManagerInterface.php
src/Ilios/CoreBundle/Entity/Manager/RecurringEventManager.php
src/Ilios/CoreBundle/Entity/RecurringEvent.php
src/Ilios/CoreBundle/Entity/RecurringEventInterface.php
src/Ilios/CoreBundle/Entity/Offering.php
src/Ilios/CoreBundle/Tests/Fixture/LoadOfferingData.php
src/Ilios/CoreBundle/Tests/Fixture/LoadRecurringEventData.php
src/Ilios/CoreBundle/Tests/Entity/OfferingTest.php
src/Ilios/CoreBundle/Tests/Entity/RecurringEventTest.php
src/Ilios/CoreBundle/Tests/DataLoader/OfferingData.php
src/Ilios/CoreBundle/Tests/DataLoader/RecurringEventData.php
src/Ilios/CoreBundle/Tests/Controller/RecurringEventControllerTest.php
src/Ilios/CoreBundle/Tests/DependencyInjection/IliosCoreExtensionTest.php
src/Ilios/CoreBundle/EventListener/UpdateOfferingTimestamp.php
src/Ilios/CoreBundle/Controller/RecurringEventController.php
src/Ilios/CoreBundle/Form/Type/OfferingType.php
src/Ilios/CoreBundle/Form/Type/RecurringEventType.php
src/Ilios/CoreBundle/Resources/config/managers.yml
src/Ilios/CoreBundle/Resources/config/dataloaders.yml
src/Ilios/CoreBundle/Resources/config/routing.yml
src/Ilios/CoreBundle/Resources/config/handlers.yml

[stopfstedt]

closed via #950