Cache fixes

Basically what i did is:
1. Entry Result object and Playlist Result object extends KalturaResultObject and not KalturaUiConfResult
2. Removed cacheSt from cache files name and use it to invalidate the cache
3. Removed Referrer from uiConf cache file name
4. Removed isCarousel code ( not needed any more )

Things we still need to check for:
1. Caching entries with access control, we still don't have a clear way to know if entry has access control.
2. Caching the iframe payload for entries with access control ( the same as above )

Please review