Closes #73 and #74 Show scheduled status/date for talks via events

Talks uses it's Event for a date if it has one.  I created a helper to use in the view, and added a style for the status.  I didn't remove the scheduled_date column from talks but its seems pointless to have this there.  Updated the tests and added another one for the helper.  Let me know.

![screenshot 2014-09-12 18 19 46](https://cloud.githubusercontent.com/assets/3166322/4259115/4d44fb18-3ae4-11e4-953c-b121b81c77be.png)

I don't think we actually care about this stuff. I would rather see all of the upcoming talks on the talks page rather than have this logic deciding which ones to show. I think this has been working the way we want because we never did anything with scheduled_date.