a couple of library cache clearing methods and moves them to CacheHelperExtensions. Fixes #U4-1653 for 6.1 and updates ExamineEvents to
ensure that Examine re-indexes media on all of the correct events (including Trashed). Changes for Caching are being done to begin work with
CD-148
signatures of IApplicationEventHandler methods to accept an UmbracoApplicationBase object instead of UmbracoApplication. This allows
us to execute all IApplicationEventHandler's outside of the web context. Added unit test to support booting the application outside of the
web context.
