Changed the module facility a bit to make it even easier to use
standard Python packaging/installation/path management for mavproxy
modules and still prevent naming conflicts.

Now when you issue "module load <module>" to mavproxy, it tries to
load a module named "mavproxy_<module>".  The modules that come with
mavproxy are still in the modules subdirectory, but now that directory
is added to sys.path.
fixes for new module layout from John Wiseman
use cv2.cv API
fixed CUAV.camera module
added packaging information for MAVProxy
cuav: update for new CompositeThumbnail API
fixed old import statements
camera: added filter_type setting
camera: added fullres option
export mavproxy_CUAV from MAVProxy.git (with history)
Merge branch 'slipmap-refactor' of ../MAVProxy into slipmap-refactor