Pluggable implementation for distinction between private and public IPs

[barakm]

The Openstack provider decides whether an IP is Private or Public based on the IP ranges defined here:
https://github.com/jclouds/jclouds/blob/master/core/src/main/java/org/jclouds/util/InetAddresses2.java

Basically, IPs matching 10., 172. and 192.168.* are considered private, everything else is public. This works well for public clouds but does not really work for private clouds, where the node 'public' IP is actually an IP in a reachable local network and is likely to be in one of these 'private' ranges.

A discussion of how to make this behavior pluggable is available here:
https://groups.google.com/forum/?fromgroups=#!topic/jclouds/jjLfZ08iOYQ