Loopback adaptor issues on Windows

JIRA: http://jira.jboss.com/jira/browse/JGRP-79

On Windows, when a loopback adaptor is created, we can associate multiple (virtual) IP

addresses with it, e.g. 10.0.0.1 and 10.0.0.2.

However, when we have a member M1 bound to 10.0.0.1, and another member M2 bound to 10.0.0.2, and

bind_to_all_interfaces is set to true, then it was observed that - regardless of the bind address -

the sender's address in a DatagramPacket received was always 10.0.0.1 (the first address assigned) !

Therefore, members would never find each other.

The reason this shows up now (in 2.2.8) is that as an optimization, we don't send the src address

in the Message anymore, so we can save a few bytes, but we null the src address, and set it to the sender's

address when we receive the packet.

This can be disabled by setting null_src_addresses to false (default is true)