Re-applies the ideas of r9718 with a refined implementation on the PulseAudio Renderer in order to reflect changes to the user's choice with respect to the default playback device while in a call.

Temporarily reverts to the PulseAudio Renderer implementation to a pre-r9718 state to fix freezes reported by Vincent Lucas and Kertesz Laszlo on the dev mailing list while further looking into the cause of the problem.

Moves the ConfigurationService and FileAccessService implementations from Jitsi into libjitsi. Silences handled exceptions in libjitsi by converting them into Logger informational messages.

Updates the detection of a remote desktop sharing call via the new Controls of imgstreaming.DataSource, in order to display a desktop icon as the local visual.

Commits an initial version of the libjitsi library which should be fully functional with respect to neomedia/MediaService and should be usable with and without OSGi.