Bugfix BCDevOps#10 Remove mirror specificity of epel package source

There is no need to target a specific mirror to acquire the epel release.
We can instead target the default general release instead and achieve the
same end result.

Signed-off-by: Jeremy Ho <jujaga@gmail.com>

docker/Dockerfile

@@ -20,7 +20,7 @@ RUN set -x && \
     certbot --help paths
 
 RUN set -x && \
-    yum install -y https://mirror.csclub.uwaterloo.ca/fedora/epel/epel-release-latest-7.noarch.rpm && \
+    yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm && \
     yum install '--disablerepo=*' '--enablerepo=epel' -y jq && \
     curl -sfL https://github.com/openshift/origin/releases/download/v3.11.0/openshift-origin-client-tools-v3.11.0-0cbc58b-linux-64bit.tar.gz -o /tmp/openshift-origin-client-tools.tar.gz && \
     tar -xzvf /tmp/openshift-origin-client-tools.tar.gz -C /usr/local/bin --strip-components=1 openshift-origin-client-tools-v3.11.0-0cbc58b-linux-64bit/oc && \