added 'slideUp' transition, autoClose, transitionClose, changed delegate / bind to on

* added 'slideUp' transition to have overlay rise from the bottom to the top
* autoClose will close overlay automatically if milliseconds are provided
* added transitionClose to specify which transition to use on close.  If not provided close will use the transition.
* changed delegate, undelegate and bind, unbind to on and off -- this will change will require jQuery 1.7 and higher (this could be easily reversed)