Updating GNU Telephony

While we haven't used sourceforge, I think in a few years, git makes it particularly easy to push and manage additional remotes. Also, as we are preparing to update all our code around ucommon API release 6 (ucommon 6.0.0), and with it release and distribute updated sets of our core applications and services (including sipwitch 1.4), this seemed like a particularly good time to re-introduce sourceforge. As we produce and update these releases we will also make them available here.