ncks "append mode" is broken

[kwilcox]

The code to retrieve the version of NCO is currently broken:

  File "/home/kwilcox/miniconda3-py36/envs/packrat35/lib/python3.5/site-packages/nco/nco.py", line 224, in get
    nco_version = self.version()
  File "/home/kwilcox/miniconda3-py36/envs/packrat35/lib/python3.5/site-packages/nco/nco.py", line 364, in version
    ncra_help)
  File "/home/kwilcox/miniconda3-py36/envs/packrat35/lib/python3.5/re.py", line 173, in search
    return _compile(pattern, flags).search(string)
TypeError: cannot use a string pattern on a bytes-like object

When specifying the append flag (-A) in ncks, the version() function is called resulting in errors. We need some test coverage for the append ncks functionality!

$ python
Python 3.5.3 | packaged by conda-forge | (default, Feb  9 2017, 14:37:12) 
[GCC 4.8.2 20140120 (Red Hat 4.8.2-15)] on linux

[kwilcox]

Working on a PR...