Add CVS import scripts and programs

This gets the "cvs2git" program from the old git-tools
archive, and adds a nice script around it that makes it
much easier to use.

With this, you should be able to import a CVS archive
using just a simple

	git cvsimport <cvsroot> <module>

and you're done. At least it worked for my one single test.

NOTE!! This may need tweaking. It currently expects (and
verifies) that cvsps version 2.1 is installed, but you
can't actually set any of the cvsps parameters, like the
time fuzz.