Format for configuration files

[davidrpugh]

@EconomicSL/core-devs We need to start thinking about configuration file solutions and formats. This issue is somewhat related to issue #6 on DI.

I have used a Java-Scala library called typesafe-config but I am not sure how this solution would interact with our chosen DI framework. I think ideally, we want to present a user with a single, structured but human readable configuration file that can be used to tune all of the relevant parameters and behavioral/decision rules.