gitdm: Add gitdm configuration

gitdm: Add gitdm configuration

This configuration can be used by gitdm to generate reports about
libvirt development.

The goal I was working with was being able to generate a report
for every single libvirt release and having zero "email address
as company" entries; picking different commit ranges might result
in some contributions not being accounted for.

I had to make some judgement calls when the situation was not
entirely clear-cut: when in doubt, and not finding any obvious
signs of the opposite being true, I mostly ended up dumping
people in the "unaffiliated contributions" bin. If I got it
wrong, and companies want to get recognition for their sponsored
contributions to libvirt, they can send patches.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>