Stop accepting resin-compose.yml as a build composition definition
Stop accepting resin-compose.yml as a build composition definition

These files are not supported by any other part of the resin
infrastructure, and it could cause confusion with it not being
supported everywhere. The idea was originally added because we
thought we might need to make extensions on docker-compose, but
that hasn't happened.

Change-type: major
Signed-off-by: Cameron Diver <1d572acbfa68c7c6e541c7b840d6b622e5c0dc91@resin.io>

resin-io/resin-cli,resin-io/resin-cli,resin-io/resin-cli,resin-io/resin-cli