Hangouts flow on events show page

PT stories: 
https://www.pivotaltracker.com/story/show/71654160
https://www.pivotaltracker.com/story/show/73873708

UI clean up
extracted styling to sass
added Join Live link on event show page

increased Capybara default timeout for javascript driver

demo: http://yaro.herokuapp.com
also the order is now reversed (might impact some CSS), `application.css` is now loaded after the other components (whereas before it was loaded before)