Currently the Service section of the Bravefile is required during build since it defines the name and version of the image to be built.
It's also necessary to provide the name of the service container that will be deployed from the image at build time.

To better separate these steps, it would be better to define the image (name+version) that's being built within the build section of the Bravefile. This would make it possible to have a Bravefile without a Service section, and clearly splits the build and deploy stages.

To avoid too much unnecessary repetition of fields and maintain backward compatibility perhaps we can read the Image name from Service section if it is not provided in build section.