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
why not just use one `strftime`?:

~~~ruby
time.strftime("%A, #{time.day.ordinalize} %b at %I:%M%P (UTC)")
~~~