Also add convenience functions for getting user-groups (and their objects) from WordPress's taxonomy global.

This makes it much easier to work with user-groups in third party code, as it's now possible to use WordPress's internal taxonomy register to retrieve which taxonomies are grouping users together instead of posts.

Also bump to 0.1.5.

jQuery.live() was deprecated in 1.7

Uses .on() (w/delegated event) instead.  Also uses $ alias that is made available, rather than jQuery.