wireless-regdb: Update keys and maintainer information

As announced by John [1], I'm taking over maintaintership of the
wireless regulatory databse. Make it official by adding my key,
removing John's, and updating the Makefile and documentation to
reflect the change in maintainer.

[1] http://permalink.gmane.org/gmane.linux.kernel.wireless.general/131573

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>