Fix for working with python3 (ST3)

shlex.split cannot handle bytes, and since python3 does not ignore anymore the b prefix of the strings (to the contrary of python 2.x), shlex.split will fail like this:
....
   opts += shlex.split(output[0])
  File "X/shlex.py", line 276, in split
  File "X/shlex.py", line 266, in __next__
  File "X/shlex.py", line 93, in get_token
  File "X/shlex.py", line 121, in read_token
AttributeError: 'bytes' object has no attribute 'read'

Thus it's required to decode the string.