custom template has disabler tag present by default

Should we disable custom configuration by default. It may be confusing for new users when trying to provide custom config. I'd say that when choosing custom template, I'm serious about using it and disabler tag can be easily overlooked.

https://github.com/jboss-container-images/jboss-amq-7-broker-openshift-image/blob/amq-broker-71-dev/templates/amq-broker-71-custom.yaml#L236