Correcting Syntax for Docker

Updates the syntax for the sed scripts so that the DOCKER_PROXY_URL
is correctly expanded

Change Makefile so docker images are pushed to gitlab, not
dockerhub

Change-Id: I6cd66711de8fc79146613aa84d79ca234e6d17c1
Signed-off-by: beierlm <mark.beierl@canonical.com>
diff --git a/docker/mk/Makefile.include b/docker/mk/Makefile.include
index e151748..995cbdf 100644
--- a/docker/mk/Makefile.include
+++ b/docker/mk/Makefile.include
@@ -26,6 +26,7 @@
 REPOSITORY_KEY  ?= OSM%20ETSI%20Release%20Key.gpg
 REPOSITORY      ?= testing
 NO_CACHE        ?= --no-cache
+DOCKER_REGISTRY ?= ""
 
 LOWER_MDG = $(shell echo $(MDG) | tr '[:upper:]' '[:lower:]')
 
@@ -81,7 +82,7 @@
 	rm -f $(MKBUILD)/.dep*
 
 tag:
-	docker tag opensourcemano/$(CONTAINER_NAME):$(INPUT_TAG) opensourcemano/$(LOWER_MDG):$(TAG)
+	docker tag opensourcemano/$(CONTAINER_NAME):$(INPUT_TAG) $(DOCKER_REGISTRY)opensourcemano/$(LOWER_MDG):$(TAG)
 
 push: tag
-	docker push opensourcemano/$(LOWER_MDG):$(TAG)
+	docker push $(DOCKER_REGISTRY)opensourcemano/$(LOWER_MDG):$(TAG)