Minor changes

We've made various improvements in relation to an internal Node.js project;

 - Works as a Node.js module (we published it as `ical.js-one.com` for now)
 - Keeps track of parent VTIMEZONE
 - Implemented `findChange`-method
 - Split utcOffset (we need to tinker in it's internals, AFAIK)

(Heads up, @papandreou)