Fix listing of tracks, and subsequent talk listings

This fixes the "Tracks" button on an event's detail page, to fetch the tracks, list them accordingly, and then allow viewing of talks filtered by that track.

Track listing (as per previous app):
![track-listing](https://f.cloud.github.com/assets/231551/2305454/b7068d6c-a257-11e3-9133-d2b4c069b795.png)

and talks listing filtered by a selected track (see action bar subtitle):
![track-talks](https://f.cloud.github.com/assets/231551/2305456/c1024ae0-a257-11e3-9123-ca8f0719117a.png)