Add cli

[Wikilicious]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 48.05195% with 40 lines in your changes missing coverage. Please review.

Project coverage is 90.50%. Comparing base (a4b04a4) to head (0639cbd).

Files	Patch %	Lines
pygmc/cli.py	38.46%	40 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #119      +/-   ##
==========================================
- Coverage   93.65%   90.50%   -3.16%     
==========================================
  Files          20       21       +1     
  Lines        1072     1137      +65     
==========================================
+ Hits         1004     1029      +25     
- Misses         68      108      +40     

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[Wikilicious]

Was expecting codecov/* to fail... due to punting cli tests.

However, it seems the linter changes are breaking non-happy-path usage...
i.e. python -m pygmc.cli -h works but python pygmc/cli.py -h doesn't

Not merging till the latter noob case works

[Wikilicious]

Added GRC (Gross-Reality-Check) test for CLI...
Want to put this out in the wild to see if any issues popup before releasing new version.

[Wikilicious]

closes #68