Makefile header conversion script

[Emanuel Haupt]

I have just added Tools/scripts/convert-makefile-header.pl, a script
that can help you convert old style Makefile headers to the new format
which was announced a while ago:

http://lists.freebsd.org/pipermail/freebsd-ports/2012-September/078319.html

Here is a list of maintainers that agreed to let people remove "created
by" lines:

http://wiki.freebsd.org/Ports/MaintainerTrimming

Please do not submit PR's changing only the header. Update headers only
with regular updates.

Emanuel