Such configurations can be specified in a properteis file outside of the war (or
webapps/hapi-fhir-jpaserver) and the server may be instructed to load the configuration using
-Dhapi.properties=<path-of-external-configuration-file>
This is helpful in at least two use cases:
1. Deploying multiple instances with different configurations (e.g., differnt databases)
2. Future upgrade - just update the war without the need to change hapi.properties after update.
