Add ability to use ServiceNet for file transfers

[As before, but on it's own branch...]

ServiceNet is Rackspace's term for their internal cloud network. Unlike traffic going through the public internet, bandwidth on this network - say between a web server and cloudfiles - is not charged.

This change enables users to use ServiceNet for file transfers. See the same change in ZF1:
http://framework.zend.com/issues/browse/ZF-12318