Hangouts feature

First step for Hangouts feature: autoupdating the link to hangout after it was started.
PT story https://www.pivotaltracker.com/story/show/71654160

User presses Hangout button -> Hangout gets started -> an application (WebsiteOne connection service) starts inside the Hangout -> the application reports the hangout url to WebsiteOne server -> the link is updated.

The application for Hangout is at http://yaro.i234.me/websiteone.xml
We should create a repo at AV for this application.
An extra instance variable isn't required here, you should access `@event.hangout` from the view.