link from devhub to commbadge (bug 907569)

Previous attempt: https://github.com/mozilla/zamboni/pull/1073

Create a link in the developer hub to a Communication Dashboard.

The Communication Dashboard uses the commonplace/index.html template with some added ```block```s to include some devhub CSS, add some extra components, and override some small things.

Created a commbadge CSS file to work out the small kinks of just throwing devhub CSS in.

Screenie
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![screen shot 2013-09-03 at 12 27 08 pm](https://f.cloud.github.com/assets/674727/1075485/db675338-14ce-11e3-84ef-0af11079142a.png)

![](http://i.imgur.com/wc60kA6.gif)