Add documentation for Red Hat install.

Hi Jon-

I wrote up a guide to installing on Red Hat, after many trials and tribulations. I think it's pretty self-explanatory, but you'll want to make sure everything is acceptable. In particular, Red Hat required a slightly older version of the Kakadu binaries. The documentation says that it needs at least version 7.0, but I'm not sure what exactly changed. As far as I can tell (in my relatively simple testing so far) everything seems to be working properly with version 6.

-Michael