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

@@ -1,6 +1,6 @@
 # This image provides a Python 3.5 environment you can use to run your Python
 # applications.
-FROM registry.fedoraproject.org/f26/s2i-base:latest
+FROM registry.fedoraproject.org/f28/s2i-base:latest
 
 EXPOSE 8080
 
@@ -14,7 +14,6 @@ ENV PYTHON_VERSION=3.6 \
 
 ENV NAME=python3 \
     VERSION=0 \
-    RELEASE=1 \
     ARCH=x86_64
 
 ENV SUMMARY="Platform for building and running Python $PYTHON_VERSION applications" \
@@ -35,7 +34,6 @@ LABEL summary="$SUMMARY" \
       com.redhat.component="$NAME" \
       name="$FGC/$NAME" \
       version="$VERSION" \
-      release="$RELEASE.$DISTTAG" \
       architecture="$ARCH" \
       usage="s2i build file:///your/app 26/python3 your-app" \
       maintainer="SoftwareCollections.org <sclorg@redhat.com>"