Maven integration, 0.20.5 update, IP whitelist, CORS support

Some more info here #5

When reviewing my own code: authenication is enabled by default. Is that okay?

> enabledByDefault = true;

Also regarding the IP whitelisting: For load balancing one needs to grab the xForward header instead of the host. But I couldn't get this to work (for AWS) although the property "X-Forwarded-For" should be correct. Probably elasticsearch removes this from the request or whatever :/