CDK-643: Initial draft of how to use maven with Kite

* Mostly this just documents the warning about how configuration files
  can be pulled into the build.
This is confusing. We will produce a different build based on environment variables? That sounds prone to error if we only intend for the environment variables to be used for testing. I thought we only intended to make the maven plugin respect these options, rather than having it include the files in the build. To do that, I think the user should have to put them in src/main/resources.