Add man pages.

Most of these are fairly simplistic, but it's a starting point.

In addition to the generated roff pages (suitable for `man` viewing),
there is a Rake task that will create and publish nice HTML versions:

   http://ifixit.github.com/git-scripts/

I was going to make a task that would copy the man pages in to the
appropriate section on the system, but it seems converting this
repository into a gem and letting rubygems handle that would be better.