Adding Base Images test to cafe kit

* The base images test attempts to build one server of image available
  in an environment. It will attempt to find the smallest allowed
  flavor for the image.
* Added the base-images tool. This takes a <product> and a <config>
  and attempts to run the base-images tool against the environment/
  user in that environment.
* Added base-images-pool tool. This takes a <produce>, a <config> and
  the option argument <--pool>. This uses a connection pool in order
  to allow controlled multithreaded behavior. The --pool argument
  defaults to value 5 if not entered. The connection pool will start
  n threads(where n is the value of pool) at a time and will continue
  running n threads until all threads have completed.
You don't need to do everything from here on down. If you create a Compute Composite object, it takes care of all of this (https://github.com/stackforge/cloudroast/blob/master/cloudroast/compute/fixtures.py#L39)