If TCP is passed in as the protocol, by default, we add TCP as the
protocol within the Kubernetes or OpenShift artifacts.
By default, TCP is already selected within Kubernetes and thus having
the TCP output is redundant.
This commit checks to see if TCP has already been selected, and if it
has, ignores adding it to the list of ports.
Closes https://github.com/kubernetes-incubator/kompose/issues/392
Volume constraint is missing in mariadb service
in etherpad example, so added that so that it mariadb container
does not fail in environments where creating container in
/var/lib/mysql is not allowed for non-root process.
