[API] removed StreamService component

R.I.P threading and error prone *beast*. I will make changes to the
network layer allowing to gain better access to custom connections which
was the only reason this component was developed for as *workaround*.

This patch also removes remaining artifacts from the VOIP feature.

Change-Id: I57210f521322f4e6a7fe232cf1ccf43f177277c5
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1350
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Tested-by: Jenkins CI