Added processing of rrule-events in ical view

I added rrule.js for processing of repeating events in ical view.

Sorry for the git mess - I am new to git and don't know how to prepare a cleaner repository / branch with only the rrule.js changes.

Please look at:
- index.php
- js/main.js
- js/rrule,js
- js/nlp.js (not sure, if needed)

I also updated "moment.js" to the current version (moment-with-locales.js)