fixed displaying "View more" button by creating computed property
extracted onscroll handler in GalleryMediaComponent and overwritten load method in LinkedGalleryMediaComponent to load all 4 images at the beginning
HG-418 show the chevron only when an image is linked
HG-417 added compression function to sort media - not linked media first
fixed TypeScript errors
added unit test for sorting in LinkedMediaGallery
Merge pull request #412 from Wikia/HG-366

HG-366, HG-417, HG-418 Various fixes for linked images in Mercury