Implement ics/ical to sync calendars with schedule

[mariobehling]

Propose and implement ics/ical to sync with calendars.

[dilpreetsio]

@mariobehling This is a great feature for the webapp. The speakers and users can add the sessions to their calendars. I have proposed something similar in my GSOC proposal letter. The idea is to create a calendar, and provide a button for sessions which will let them save the sessions directly to their calendar. I have proposed to use google calendar api, for creating a public calendar with all sessions added to it.

[mariobehling]

@geekyd Thanks for your input. This would be a different issues. As a first step I am looking at a complete calendar with one button instead of single sessions. We can follow up on the single sessions later. We also need to think about updates, but this comes later. Step by step.

[Princu7]

@mariobehling Just to be sure, we want to provide a button to the users that will export the whole schedule of the event to an ics file on click? Please guide. Thanks!!