Added initial conference delete and archive functionality
Added the necessary database migration to add the archive column to the conferences table. Removed the archive method from ConferenceResource.java since it will be covered by the update method. Added the new member varibale and methods to Conference.java.
Added functional tests for conference delete and archive functionality.
Updated tests for archive and delete conferences, still not quite working.
Now returning the proper "404 - Not found" response
Incorporated Ryan's suggested changes and added a couple tests for various archive and delete situations.
Merge pull request #163 from CruGlobal/feat/delete-conference

Feat/delete conference