Fix Python error

Error message I was seeing:

Traceback (most recent call last):
  File "bin/sparkler", line 179, in <module>
    sparkler_cli()
  File "bin/sparkler", line 171, in sparkler_cli
    guid = hashlib.sha1(''.join(raw_values)).hexdigest()
TypeError: Unicode-objects must be encoded before hashing

I'm using Python 3.3.3, not sure if that was the cause of my error or not.