Move configuration to global location

[nickjer]

Currently the ood-portal-generator configuration exists under the installation path for ood-portal-generator. This typically is in the home directory of the person who installed Open OnDemand.

This causes the configuration file to be easily lost or the sys admins forget about it and directly edit the Apache config.

A simple solution is to:

• read the ood-portal-generator YAML configuration file from a well-defined global location such as /etc/ood/config/ood-portal.yml
• leave verbose documentation in the Apache config about not directly editing the Apache config but instead to use the global ood-portal-generator configuration file