man/README: add syntax/workflow information for the man pages
md2nroff.pl: updates for "make nroff" and cron job

Corrections to make md2nroff.pl only write new output when there are
actual changes (besides the date).
man: script to run via cron that updates man pages

This script syncs the master:man/*.md files to gh-pages:master/man/
(i.e., the live web site) and updates the rendered nroff files in
master:man.

It basically does the following:

1. Check out the master branch from the repo.
2. Check out the gh-pages branch from the repo.
3. Copy master:man/*.md to gh-pages:master/man.  Commit and push
   (which will be a no-op if nothing has changed).
4. Run md2nroff.pl on each master:man/*.md file.  Commit and push
   (which will be a no-op if nothing has changed).
Merge pull request #326 from jsquyres/pr/man-page-automation

More man page automation