Fix the configuration loading

[BenjamenMeyer]

Configuration is loaded from only a couple files specified in rse/__init__.py, one of which (rse.default.conf) no longer exists in the source tree or in a way that can be located as described in rse/__init__.py. This needs some heavy refactoring to fix.

Suggestions:

• make a new rse/config.py that deals with the configuration data
• provide a means for the default file to be overridden for easy use in unit tests

[BenjamenMeyer]

WORK AROUND: test via docker

$ docker-compose build
...
$ docker-compose up

Then run something against the RSE service on the docker container. By default, it uses Mimic as the auth backend. A good test might be to configure it for Public Identity and then run something real against it.

[BenjamenMeyer]

See Issue #42 per unit tests