Exception thrown when trying to log error in resources/cluster/deploy_software()

[tvoran]

Triggered by specifying an invalid ssh_priv_key:

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/local/Cellar/python/2.7.4/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "automaton.py", line 60, in run
    cluster.deploy_software()
  File "/Users/voran/projects/git/automaton/resources/cluster/clusters.py", line 206, in deploy_software
    LOG.error("Deploy_software: " + command.stdout)
TypeError: cannot concatenate 'str' and 'NoneType' objects