App: Setting up Environments

[nicseltzer]

Implement a way to determine the environment in which the application is currently running. It should be possible to reference the current environment from any aspect of the application for the purposes of altering the behavior of the application at runtime (e.g.: DEBUG logging should be present at runtime in DEV/TEST, but not in PROD).

This will relate to the way that we do database selection between local dev and other environments.