Add basic hashing functionality to imgur

* There is probably a much nicer way of doing it (perhaps a better
  hash)?
* Added a counter to the imgur random page counting the number of
  [Facebook Monopoly Men](http://i.imgur.com/3Tt6N.gif).
* Added the md5sum of the current image to the getRandomImage api call.
* Future functionality might be storing every image md5 in an array and
  counting duplicates, instead of the current check-against-known-dupes.