Boyscout: improve factoring of Arrthorizer::Rails::Configuration
Boyscout: improve factoring of Arrthorizer::Rails::Configuration

It is now easier to a) insert a fake configuration when testing and b)
change the configuration file location. Refs #18

BUS-OGD/arrthorizer,BUS-OGD/arrthorizer,BUS-OGD/arrthorizer