packaging and test cleanups

[msimerson]

Changes proposed in this pull request:

• remove grunt entirely
  • most grunt functions weren't used frequently enough to justify maintenance
  • greenkeeper.io replaces the most useful grunt versioncheck
• replace @godsflaw customized nodeunit tests with standard nodeunit tests
  • faster to install from npm than github
  • the @godsflaw PR from 2012 Added asserts from Christian Johansen's Test-Driven Javascript Development book caolan/nodeunit#153 hasn't progressed
  • the last person to maintain the forked nodeunit was me in 2014

Checklist:

• docs updated
• tests updated

[msimerson]

This PR shaves a full minute off our Travis CI build times.

[codecov-io]

Current coverage is 34.44% (diff: 100%)

Merging #1754 into master will not change coverage

@@             master      #1754   diff @@
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  Files            23         23          
  Lines          5917       5917          
  Methods         762        762          
  Messages          0          0          
  Branches       1500       1500          
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  Hits           2038       2038          
  Misses         3879       3879          
  Partials          0          0          

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