Add automatic jsonlint test with travis-ci for acceptance testing

This adds a Grunt task for automatically running jsonlint on all of the data files.  It also moves the data file subdirectories into a `data/` directory so they can more easily be referred to.

Two things worth doing before merging:
 - You'll probably want to look at the values in `package.json` and change any descriptions you want.  I went with some defaults here, but needed to add in a package file so I could have `devDependencies` for travis-ci to recognize.
 - As the repository owner, you'll need to go to [travis-ci.org](http://travis-ci.org) and authorize your account and then turn on continuous integration for this repo.

From that point on, all pull requests should be automatically linted and the test status will show on the pull request.  (I'm not 100% certain I got this correct since I can't debug the actual travis-ci part until it's turned on, but once it's turned on I think we can see the results and I can update this PR if needed.)