Support negative selectors for AJAX links

I encountered a use case where we needed all the links in a specific container AJAX-ified ... but not a few of them. Since the triggers are just jQuery selectors, we're able to do that with some selector magic. Unfortunately, there are cases where selectors won't work including links like contextual links which are in the container we are selecting.

As an example, if you have #main a as a selector, this will select contextual links. But with the patch below you can remove contextual links from the selected elements by adding !.nav a. The "negative trigger" is then removed from selected elements using jQuery's .not method.