Add social.ambient-notification sent to the browser to provide status icon changes in post-FF 28 builds

Post FF28 (well, [bug 935640](https://bugzilla.mozilla.org/show_bug.cgi?id=935640)), we need to be sending the social.ambient-notification to update the status icon in the toolbar for the connected/disconnected status.

This has been pair-programmed by @dmose and @Standard8.