Actually tag the actual images we make

Well, making an image and not tagging it is just lame, because then it's
just, well, a uuid. And nobody likes uuids.

Change-Id: If8cfd530499aa9574703ac2a95eb306bc10d9b6b

pbrx/container_images.py

@@ -239,6 +239,7 @@ def build(args):
                     "Building container for {script}".format(script=script))
                 with docker_container(
                     info.base_container,
+                    tag=script,
                     prefix=args.prefix,
                     volumes=[tmp_volume],
                     comment='CMD ["/usr/local/bin/{script}"]'.format(