JSHint Updates

* JSHint failures now trigger errors for `make validate`
* Updated `.jshintrc`
* Fixed existing errors

@rocha @dsjen 
What if we change `validateQuoteMarks` to `{ "mark": "'", "escape": true }`.  It would be nice for us to be able to use double quotes instead of single quotes, http://catatron.com/node-jscs/rules/validate-quote-marks/.