Per-environment configs

[rsyring]

• Need to be able to specify different config for different environments
• Some type of list of used/approved environments. If you have the config for each, you can use that. But then for the devs, there's going to be different environment names (e.g. rsyring.meld). Maybe the environment name in that case is always "dev" but a different ident is used in the config for the special case of "dev" environment so that any objects created in AWS have the dev's preferred ident (e.g. rsyring.meld).
• A simple app with no config for the different environs could probably give a static list of expected environment names.
• Maybe rename "environment" in this context to "profile" to avoid overloading "environment"