Avoid errors with jQuery used in noConflict mode

I found out that hashgrid would not work after [jQuery.noConflict()](http://api.jquery.com/jQuery.noConflict/) since it's using `window.$` instead of `window.jQuery`. 

For example, Wordpress does this this after it's done using jQuery for its own purposes.

I fixed this by redefining `$` inside `hashgrid()` and using `jQuery()` to initialize the script.