Tidy up a bit

docker/Dockerfile-el7

@@ -0,0 +1,15 @@
+# Dockerfile.rpm
+
+ARG DISTRO=oraclelinux
+ARG RELEASE=7
+
+FROM ${DISTRO}:${RELEASE}
+
+RUN yum install -y \
+    rpm-build \
+    make \
+    oracle-epel-release-el7 \
+    && yum clean all
+
+WORKDIR /src
+CMD ["make", "package-rpm"]