hint + various enhancements

While learning my way through gulp, I did some work on this, and would love to have some input on whether these are welcome or not. I would definitely amend (or close) this pull-request according to your indications.

* moved away from Makefile and grunt (referenced in travis) to a gulpfile that does "hint" and "mocha"
* various changes in the plugin itself (moved to through2, better erroring)
* fixed jshint reported violation