[API] added JmDNS library

Added the JmDNS which will be used for further development to enable
sessions by just using plain TCP without the need for a XMPP
server.

Change-Id: Id17c1c21b0ed75a6c05d11f11875db1fcf831e10
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1552
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>