Clean up + extend figure7_real code

* Add in Greedy Edge tests for mandrill image
* Change size of scaled down image to avoid clipping (64x64 instead of 51x51)
* Tune down number of rounds for computing correlation. more seems better,
  but don't need 1000 to get good results. Would be nice to do an experiment to
  see how much this affects error rate. Maybe future work?