Uploading images to a local registry fails (make docker-push-image problem)

[kzorba]

While creating a gitlab pipeline to build and upload the images to an internal registry, I noticed the images could not be uploaded.

The error was:

invalid reference format: repository name must be lowercase

The problem appears to be in docker-push-image target in the makefile.
I made a small patch for this in makefile.include, a pull request will follow.

Best regards,
Kostas