add ability for ribbon/eureka to use ipAddr instead of hostName configed...

add ability for ribbon/eureka to use ipAddr instead of hostName configed via Archaius

this relates to the discussion on the mailing list here:

https://groups.google.com/forum/#!topic/eureka_netflix/7M28bK-SCZU
This is not necessary once the DefaultClientConfigImpo.loadDefaultValues() calls appropriate method. See my previous comment.