VID-1957 New screenshot for labs page
VID-1957 Enable new galleries in labs
Merge with VideoSprint58
Merge branch 'VideoSprint58' into VID-1957

Conflicts:
	extensions/wikia/MediaGallery/MediaGalleryHooks.class.php
Merge pull request #4933 from Wikia/VID-1957

Enable MediaGallery extension in Labs