Add git-shortlog perl script

Add git-shortlog perl script

Somebody finally came through - Jeff Garzik gets a gold
star for writing a shortlog script for git, so that I
can do nice release announcments again.

I added name translations from the current kernel history
(and git, for that matter). Hopefully it won't grow at
nearly the same rate the BK equivalent did, since 99% of
the time git records the full name already.

Usage: just do

        git-rev-list --pretty HEAD ^LAST_HEAD | git-shortlog

or, in fact, use any of the other tools (git-diff-tree,
git-whatchanged etc) that use the default "pretty" commit format.