prepare 2.9.0 release

Change-Id: I0e26e383dbe2f9f49bffa270d07f5c7f7405e571
Reviewed-on: http://gerrit.esdi-community.eu/3209
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>
Tested-by: Simon Templer <simon.templer@igd.fraunhofer.de>