April features

Summary of changes:
* Remove calls to jQuery live() in favor of on() to support jQuery 2.0 and beyond. This will drop support for versions of jQuery prior to 1.7.
* Add an optional welcome message to display on page load and to be conditionally dismissed either via localStorage/cookie or by an optional user-passed method
* Add an example page to demonstrate implementation of pageguide, including the new welcome message
* Bring README up to date