RSB GStreamer Integration

Ambiguous configurations of the .rst.vision.Image cause any rsb-gstreamer component to fail with a message along these lines:

0:00:00.098899690 14722      0x1614a00 ERROR                 rsbsrc /media/local_ci/jenkins/jobs/rsb-gstreamer-resume_stream_fix-toolkit-nightly/workspace/label/master/src/gst_rsb_src_base.cpp:341:gst_rsb_src_base_ensure_listener:<rsbaudiosrc0> failed to create RSB listener: Error configuring connector `spread', in-push: Ambiguous converter set for wire-type `std::string' and wire-schema `.rst.vision.Image': candidate data-types are {rst::vision::Image, _IplImage}; hint: add a configuration option `transport.<name>.converter.cpp.".rst.vision.Image" = <one of {rst::vision::Image, _IplImage}>' to resolve the ambiguity (A converter is already stored for the key `.rst.vision.Image').

It's easy to work around this issue but since rsb-gstreamer never uses _IplImage, a rule to always use rst::vision::Image would be the more elegant behaviour.

From https://projects.cit-ec.uni-bielefeld.de/issues/4218