Allow using custom jshint.js

[kryger]

Currently there's no way to use JSHint version different than the one bundled in src/main/resources/com/cj/jshintmojo/jshint/, it would be nice if there was an option to specify a path to an alternative jshint.js.

[stupenrose]

This is a good idea. Someone should do this.

Patches welcome :)

[kryger]

This doesn't sounds like a huge job, I'd be happy to create a pull request. However, it would help if you tole me which build version of jshint.js is the one that can be used with Rhino (I'm already asking this in #13); I'm hoping answer to that will save me the investigation phase :)

[stupenrose]

@kryger I responded in issue #13

[stupenrose]

@kryger I've embedded the latest jshint in the plugin. If you look at the changes I made, you should be able to figure out how to add this functionality pretty easily.