If the CF CLI doesn't support environment variables, It would be really wonderful if the file would consider environment variables. It would be more in line with the 12 factor manifesto, it would discourage people from keeping secrets in `yml` files unencrypted on disk. It would also be easier to use than creating a config file. That way people can source the env variable from features in the CI services like Travis env to encrypt variables, or they could be resolved by looking up the value from something like Hashicorp Vault, all through simple environment variable use. No odd code required to write data to a `.yml` file required.