Now you can test cuttlefish

added `rt:set_conf/2` to allow appending to cuttlefish conf files

added the ability specify an InitialConfig of {cuttlefish, [{string(), string()}]} to deploy_nodes/2

set up `rtdev:update_app_config/2` to work with cuttelfish's advanced.config IF cuttlefish is enabled, otherwise it still uses app.config.

confirmed this is working with verify_basic_upgrade

added cuttlefish_configuration test to validate cuttlefish