Live sessions - some minor changes

PT story: https://www.pivotaltracker.com/story/show/74032372

Changes:
- added ajax refresh for events show page
- added ajax refresh for hangouts index page
- flattened UI for hangouts index page
- added duration to hangouts details

Refactoring:
- combined attributes into json hash for hangout button
- extracted events show html into partials


correct me if I am wrong (I am not very good at CoffeeScript), but doesn't this mean `app` is bound to the global window object? Can we avoid assigning to the global namespace in tests?