Move documentation from gpu-cluster-images into root repo

[abrandemuehl]

The root repo has no documentation about how to use the system, and acm-uiuc/gpu-cluster-images has a link to https://www-s.acm.illinois.edu/confluence/display/PROJ/Using+the+ACM+GPU+Cluster.

This should be in this repo, and the wiki article should have more information about how to actually run code on the cluster/login to it. Currently, the wiki article is very high level, without specific details of how to use it.

[narendasan]

Right now, it reflects the state of cluster since it hasn't officially come online yet. Once the web interface is finished, it will be released with documentation.