Should have one source for prometheus-config.yml

prometheus-config.yml has become scattered between many fuse projects:

• application-templates/prometheus as a place the documentation points to
• jboss-fuse/fuse-java-openshift
• jboss-fuse/fuse-karaf-openshift
• fuse-karaf because we now have the exporter there

It would be great if we had it in one central location (like application-templates/prometheus) and then pulled it during the builds of the other projects (the s2i images, fuse-karaf, etc).