Removed use of UpdaterService from CachingVariable

The service UpdaterService can not work in the threaded framework. Therefore UpdaterService was removed from CachingVariable. In its place the CachingVariable uses the new cacheIdentifier of edm::Event to know if a new Event is being used.
Merge pull request #1455 from Dr15Jones/removeUpdaterServiceFromPhysicsToolsUtilAlgos

Multithreading fixes -- Removed use of UpdaterService from CachingVariable