bootstrap-collapse.js shouldn't rely only on transition end event

Created by: victor-homyakov

Currently methods Collapse#show(), Collapse#hide(), Collapse#transition() rely only on transition end event, and will have broken inner state and stop work if such event wasn't fired for some reason:

1. Element has method hide(), which actually hides element, thus preventing transition (http://api.prototypejs.org/dom/Element/prototype/hide/).
2. Transition is aborted because the animating property's value is changed before the transition is completed (https://developer.mozilla.org/en-US/docs/CSS/Using_CSS_transitions#Detecting_the_completion_of_a_transition).
3. Browser vendor changes transition end event name/event system, as it already was with Opera (http://www.ianlunn.co.uk/blog/articles/opera-12-otransitionend-bugs-and-workarounds/).

(for more info please read my answer to http://stackoverflow.com/questions/12715254/twitter-bootstrap-transition-conflict-prototypejs)

Invokation of callback complete() in Collapse#transition() should be guaranteed even if transition event wasn't fired, e.g. via setTimeout().