Add integration tests for (skopeo copy) against the Atomic Registry

This builds from the image-signatures-rest branch for
https://github.com/openshift/origin/pull/9181 .

Testing push, pull, streaming.

Does not test working with the other Docker registries built in
Dockerfile; I will leave that to the author of that code :)

Note that this relies on an internet connection for pulling from the
Docker Hub (which is incidentally tested by that); pushing to no Docker
Registry, neither local nor Hub, is tested by this.

The tests only run in a container because the (oc login) / (docker
login)-like code modifies files in a home directory; the new
SKOPEO_CONTAINER_TESTS environment variable should protect against
accidental non-container runs.

Dockerfile

@@ -40,6 +40,16 @@ RUN set -x \
 		< "$DRV1/contrib/boto_header_patch.diff" \
 	&& dnf -y update && dnf install -y m2crypto
 
+RUN set -x \
+	&& yum install -y which git tar wget hostname util-linux bsdtar socat ethtool device-mapper iptables tree findutils nmap-ncat e2fsprogs xfsprogs lsof docker iproute \
+	&& export GOPATH=$(mktemp -d) \
+	# && git clone git://github.com/openshift/origin "$GOPATH/src/github.com/openshift/origin" \
+	&& git clone -b image-signatures-rest git://github.com/miminar/origin "$GOPATH/src/github.com/openshift/origin" \
+	&& (cd "$GOPATH/src/github.com/openshift/origin" && make clean build && make all WHAT=cmd/dockerregistry) \
+	&& cp -a "$GOPATH/src/github.com/openshift/origin/_output/local/bin/linux"/*/* /usr/local/bin \
+	&& cp "$GOPATH/src/github.com/openshift/origin/images/dockerregistry/config.yml" /atomic-registry-config.yml \
+	&& mkdir /registry
+
 ENV GOPATH /usr/share/gocode:/go
 ENV PATH $GOPATH/bin:/usr/share/gocode/bin:$PATH
 RUN go get github.com/golang/lint/golint