Resolve licensing conflict.

The very first checkin of both pi_face_tracker/nodes/face_tracker.py
and ros2opencv/src/ros2opencv.py on May 20, 2011 by Patrick Goebel
already carry GPLv2 boilerplate at the top of the files.  Yet Patrick
creates several manifests that say BSD in them. Clearly, this cannot
be right ... and it would seem that the boilerplate in the source files
should take precedence over the weaker manifests trying to describe the
contents.  So I am changing the manifests here.  Also including a copy
of the license itself, per standard practice.