to be lazy since the db context isn't initialized yet (will speed up start a bit too), ensures that the macro/xslt caching
clearing is only done on the single server instead or re-posing another distributed call.
real instance object like IContent, this will dramatically increase performance for bulk publishing when not
in a load balanced environment. Updated methods on DistributedCache to refresh many instances at one time, this also
means we're not re-looking it back up again. Need to update media, users, templates, members and macros to use this new feature too.
old ICacheRefresher but now we can plugin 2 new providers - one for resolving a list of servers and the other to notify the servers of changes.
By default we have the configuration based providers which uses the umbracoSettings.
via this method so that all cache types are simply invalidated with ICacheRefreshers and ApplicationEventHandlers. Currently we
have calls to clear cache in zillions of places and its near impossible to tell where/when it currently happens.
