support gfycat.com and medacru.sh urls.

[jadedgnome]

gfycat and mediacru.sh urls in comments and submissions.. these domains are being used increasingly.

[4pr0n]

related comments are limited to comments that contained a URL that was able to be hashed (i.e. image URL)

I can try to scrape the "poster" image for the gifycat/mediacrush videos. That might work. This will take some time though.