Adds gyazo.com support, adds direct .mp4 link support and fixes >11 imgur album not working on gif albums

The direct linking mp4 support goes hand-in-hand with the gyazo support, since gyazo supplies MP4s for all their gif links, so all gyazo gif links are replaces with their respective mp4 links.
[Direct linking mp4 example](http://www.nasa.gov/mp4/645169main_v1218a_H264m.mp4)
[Gyazo non-gif link](http://gyazo.com/5a72871c5d808492e41c732a71dca8e8)
[Gyazo gif link](http://gyazo.com/3a087c19400cc960039a734ff66a488d) (should load mp4 version)


The regex for the >11 imgur album fix was missing the "gif" extension, so albums with gif files were falling back to the old method. [Example, shows 11 images pre-commit, 17 post-commit](http://imgur.com/a/zhRXo)