Added Image Shrink module

Basically, the image shrink module lets users choose a maximum image size for imgur images if they don't want to have to load extremely large images. For instance, a 5000px wide image of a few words doesn't need to be loaded when it can be seen perfectly fine at 1024px. It uses imgur's thumbnails, specified here: https://api.imgur.com/models/image#thumbs. Whenever an image is shrunken, a link to the original image is added to the post as well.
> Also, this shouldn't be a problem if imgur does change the hash length, as it dynamically appends the URL modifier based on where the .extension is.

Well, the problem was actually detecting whether someone had linked a shrunken one...

e.g. someone posts http://i.imgur.com/SOMEHASHh.jpg  where "h" there forces that particular size...

RES needs to know "that h is not a part of the hash" - and that's the biggest problem we ran into - we couldn't be guaranteed to know because the size of the hash varied.