Create and document outside-of-repo-code production Django/Roundware settings

[13rac1]

Could use a better explanation but this covers it:

Production Settings

The production Roundware/Django settings file used by WSGI Apache2 is stored outside of the source code directory in the file /var/www/roundware/settings/roundware_production.py. All settings in /var/www/roundware/source/roundware/settings/common.py can be overridden there. Do not modify any file within the /var/www/roundware/source directory unless you intend to maintain your own fork of Roundware Server.

[13rac1]

"Upgrade" process for existing installs after this pull request is merged:

cd roundware-server
# Assumes unmodified git clone of http://github.com/roundware/roundware-server.git develop branch
git pull
sudo mkdir /var/www/roundware/settings
sudo cp files/var-www-roundware-settings.py /var/www/roundware/settings/roundware_production.py
sudo chown roundware:roundware -R /var/www/roundware/settings
sudo ./deploy.sh

[hburgund]

tested this with the "upgrade" as well as fresh VM locally and then tried to over-ride a few different settings and it all worked as advertised.