Python3 compatibility

[olgabot]

Using qtools as-is with Python3 results in a string/bytes error.

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-9-013388eb4186> in <module>()
      1 import qtools
      2 
----> 3 qtools.Submitter([command], 'macaulay2016_featurecounts', ppn=threads, walltime='24:00:00', queue='home-scrm')

/home/obotvinnik/workspace-git/qtools/qtools/submitter.py in __init__(self, commands, job_name, queue_type, sh, array, nodes, ppn, walltime, queue, account, out, err, max_running, submit, chunksize)
    125 
    126         if self.chunksize is None:
--> 127             self.job()
    128         else:
    129             chunks = len(self.commands) / self.chunksize

/home/obotvinnik/workspace-git/qtools/qtools/submitter.py in job(self)
    257 
    258         elif self.queue_type == 'PBS':
--> 259             self._write_pbs(sh_file)
    260 
    261         if self.array:

/home/obotvinnik/workspace-git/qtools/qtools/submitter.py in _write_pbs(self, sh_file)
    307         self._write_additional_resources(sh_file)
    308 
--> 309         if self.array:
    310             if self.max_running is not None:
    311                 sh_file.write("%s -t 1-%d%%%d\n" % (

/home/obotvinnik/workspace-git/qtools/qtools/submitter.py in array(self)
    152             # self._array is the user-supplied whether or not to use the array
    153             return self._array
--> 154         elif ("oolite" in HOSTNAME) or ("compute" in HOSTNAME):
    155             return True
    156         elif 'tscc' in HOSTNAME:

TypeError: a bytes-like object is required, not 'str'