Open Atrium Shoutbox implemented as a popup palette

We are testing out some UI adjustments to Shoutbox on our internal Open Atrium to see how well they work. The Shoutbox is now implemented as a popup palette, with a count indicator in its menu item (see counter here www.flickr.com/photos/developmentseed/4340974694/). If this goes well, we might roll the changes into core.

Done