Runs a swarm in the giving working directory, assuming it was created by 
  Menorah.
  :param workingDir: absolute or relative path to working directory created by
                     Menorah

def swarm(workingDir):
  """
  Runs a swarm in the giving working directory, assuming it was created by 
  Menorah.
  :param workingDir: absolute or relative path to working directory created by
                     Menorah
  """
  name = os.path.splitext(os.path.basename(workingDir))[0]
  swarmDescriptionFile = os.path.join(workingDir, "swarm_description.json")
  with open(swarmDescriptionFile) as swarmDesc:
    swarmDescription = json.loads(swarmDesc.read())
  print "================================================="
  print "= Swarming on %s data..." % name
  _printSwarmSizeWarning(swarmDescription["swarmSize"])
  print "================================================="
  modelParams = _swarmForBestModelParams(swarmDescription, name, workingDir)
  return modelParams