support proxying maven.oracle.com

Oracle has started to publish a Maven repo with weblogic related artifacts. I expect that to become pretty popular with Oracle users since it saves TONS of time in terms of deploying the artifacts to an internal Nexus instance alternatively. We should make sure we know how to configure this so we can show customers and potentially work with Oracle to get any problems removed.

https://blogs.oracle.com/WebLogicServer/entry/weblogic_server_and_the_oracle

More info:
http://docs.oracle.com/middleware/1213/core/MAVEN/config_maven_repo.htm#MAVEN9012

E.g. there might be no index.

This could also be done as a blog post related investigation if there is no engineering budget..