added node-config and refactored tc-server-auth to use it.

@indytechcook, @gaitonde 

I wanted to get config in before I ran the s3 challenge,   Lets spend 5 minutes on this tomorrow.
Use config.get('auth0Domain), etc here.  This will fail silently.  You can also use config.has().  Read more about it here:  https://github.com/lorenwest/node-config/wiki/Common-Usage