adds frustrum culling filter

Uses the PCL Frustrum Culling filter for filtering the FOV:
http://docs.pointclouds.org/1.7.0/classpcl_1_1_frustum_culling.html

Also create a yaml file for the configuration parameters, because it's easier to maintain separate from the launch file.

The filter params for the FOV are in degrees, in order to follow the PCL convention, but I can change them to radians if you think it's better.
Could you please rename the transform cam2robot with a more self-explanatory name?