Video (VID-1417): VideosModule - added caching
 Video (VID-1417): VideosModule - updated getVideosDetail() function
Video (VID-1417): VideosModule - updated getVerticalVideos() function
Video (VID-1417): VideosModule - adding varnish cache
VID-1423 Whitespace
Video (VID-1417): VideosModule - use shared memcache for vertical videos
VID-1423 only send tracking call if module is visible/displayed
VID-1423 check for related articles instead of videosmodule visibility
VID-1423 check the right element
Merge pull request #2919 from Wikia/VID-1423

VID-1423
Merge pull request #2913 from Wikia/VID-1417

Video (VID-1417): VideosModule - added caching