first pass at setting webcam exposure
more tools to set webcam exposure

Problem seems to be that if the exposure is set from another process,
and then we run CaptureFPS, OpenCV sometimes re-initializes the camera
(??) and so our setting is lost.
set exposure from CaptureFPS itself

This seems to work reliably, as long as we capture something
(thus initializing the camera) before we set the exposure.
Merge branch 'master' of github.com:cberzan/drones-287
Merge branch 'master' of github.com:cberzan/drones-287
make cpp code compile
make debugger compile
bump roscopter version