[INTERNAL] added a dummy TCP server

Just added a very simple TCP server. It currently closes incoming TCP
connections immediately. Will be improved in later patches.

Change-Id: I83bebf382fc9055c4a5cc8872bcda4daf707e835
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1630
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>