"Add Gitter room" on project overview page

Gitter is a great way to build a community around a project, discuss ideas, and support users. We should make it easy to discover Gitter and link to Gitter on your project.

Proposal

• Add an Add Gitter room button in the same style as the existing Add readme button on to project dashboar
  • The button can link to the project badge interface, with a link to docs and the ability to link to Gitter by just typing the name of the room they have created

Project nav	Project badges

• Add a "Suggested badges" container:
  • If Gitter hasn't been added as a badge, present the Gitter row as an optional badge
  • If Gitter badge has been added and there are no suggested badges to present, don't present the "suggested badges" container
• Placeholder text should read "Room URI"
• "Learn more" should link to https://gitter.im
• Clicking a configured badge on the project home page should link to https://gitter.im/%{room_uri}

Subsequent iterations would include a complete workflow for creating the room in Gitter and automatically configuring the project badge when a room is linked to a project in GitLab. This depends on large complex changes in Gitter.

Links / references

• Gitter logo is from the small/14px version here, http://jsfiddle.net/MadLittleMods/LaoctLy3/