Add missing developers contributing to project git. Cancel "Past and
Occcasional" section and merge the people in the right categories.

Update .mailmap so that the Developer list can be easily re-generated.

Reviewed-By: Gabe Alford <redhatrises@gmail.com>

Name should be First-Name Last-Name. Map all Adam's contributions
to this preferred format.

<kbaker@redhat.com> is another person, entirely unrelated to FreeIPA.

This makes `git shortlog` report correct and consistent names and
addresses, even for past commits where the author information is
not ideal.

See git-shortlog(1)

Reviewed-By: Martin Košek <mkosek@redhat.com>