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


why did you start using CoffeeScript here? Since we already wrote most of assets in plain JavaScript, can we try and be consistent and continue to use plain vanilla JavaScript rather than introduce two ways to write the same thing?