Pull CIAPI connection credentials from the environment

Currently we hardcode the CIAPI connection credentials in the actual code (definitely a bad practise).

Cloud Foundry advocates the [12 Factor App approach of storing config in the environment](http://12factor.net/config); and provides [good tooling to support this](http://docs.cloudfoundry.com/docs/using/deploying-apps/environment-variable.html):

1.  cf set-env sets ENV variables at a deployed app level
2.  [`cf create-service user-provided`](http://docs.cloudfoundry.com/docs/using/services/user-provided.html) sets ENV variables at the space level, making them shared between all apps

Whilst supported, using ENV variables in Windows & .NET apps is uncommon.  Config stored in XML `.Config` files is more the norm, and integrated into the framework and tooling.  See http://stackoverflow.com/questions/13043530/what-is-app-config-in-c-nethow-to-use-it

How can we merge these two approaches?