Switch from node-jquery to cheerio

Hi,

I'm fairly new to grunt and js unit testing libs and on my search for nice libs I found yours and I like your approach.

I'm a windows user and sadly the packages `node-gyp` and `contexify` used by `node-jquery` don't play very well on windows. Plus this package isn't maintanied anymore.

Because of this I propose to switch to [Cheerio](http://matthewmueller.github.io/cheerio/) which is a small jQuery-like lib.
Unfortunally Cheerio doesn't support the `contents` method at the moment (but there is already a pull request (MatthewMueller/cheerio#234) for it) so I had to include a polyfill.

Aditionally I fixed the jsHint config which threw some errors with your code.