Gridappsd is not handling GRIDAPPSD_USER, GRIDAPPSD_PASSWORD properly

[craig8]

Description of issue

Currently the gridappsd container started and run from https://github.com/GRIDAPPSD/gridappsd-docker has the gridappsd-python from april deployed in it. In order to update this, to the latest version, the GRIDAPPSD_USER and GRIDAPPSD_PASSWORD must be in the environment during loading. So that needs to be added to the docker-compose file or embedded in the gridappsd container.

Adding to the docker-compose.yml file will allow the update to proceed properly and is the least intrusive to the current flow for applications.

I am going to put a pr in for the service_user here and we will see how this goes.
https://github.com/GRIDAPPSD/GOSS-GridAPPS-D/blob/develop/gov.pnnl.goss.gridappsd/conf/pnnl.goss.core.security.userfile.cfg