Drop Release label in favor of OSBS release_bump plugin.

OSBS can automatically bump the release number, for that
we just need to drop the label from the Dockerfile

See https://pagure.io/ContainerSIG/container-sig/issue/1

Signed-off-by: Clement Verna <cverna@tutanota.com>

Dockerfile

@@ -5,7 +5,6 @@ LABEL MAINTAINER "Petr Hracek" <phracek@redhat.com>
 LABEL summary="HAProxy reverse proxy for high availability environments." \
     name="$FGC/$NAME" \
     version="0" \
-    release="1.$DISTTAG" \
     architecture="$ARCH" \
     com.redhat.component=$NAME \
     usage="docker run -p 80:80 docker.io/modularityimages/haproxy" \