slight improvements to imgur content provider to not try to imagify /a/ links (album), to use https on imgur rather than a proxy, and to allow for https links to be used.  Still breaks on things like imgur.com/random and imgur.com/gallery/myAlbumName (as we can't differentiate these from valid images without using the imgur API)
Merge pull request #957 from JabbR/imgur-albums

Improve experience around imgur albums slightly