Code review comment for lp:~xfactor973/charm-helpers/ceph-functions

You might want to make use of six to deal with the py2/py3 compatibility:

  https://pythonhosted.org/six/#six.string_types

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ERROR: Failure: ImportError (No module named past.builtins)
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Traceback (most recent call last):
  File "/home/jamespage/src/charm-helpers/charm-helpers/.venv/local/lib/python2.7/site-packages/nose/loader.py", line 418, in loadTestsFromName
    addr.filename, addr.module)
  File "/home/jamespage/src/charm-helpers/charm-helpers/.venv/local/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "/home/jamespage/src/charm-helpers/charm-helpers/.venv/local/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "/home/jamespage/src/charm-helpers/charm-helpers/tests/contrib/storage/test_linux_ceph.py", line 4, in <module>
    from past.builtins import basestring
ImportError: No module named past.builtins