Improve inheritance system by using convention over configuration

[mrferris]

Remove requirements to use genesis.env, and instead we use the file names to deduce the environment name.

To make partial env files not look deployable, they will instead be called, for example, c-.yml instead of c.yml.

c-us.yml and c-us-1.yml would both remain deployable, while the latter would inherit from the former.

Will be opt-in feature, and will include helper function to convert legacy file names to use this convention.