Adds Rackconnect support, refs Issue #199

This patch depends on a change committed to libcloud that exposes the accessIPv4 argument in the Openstack driver. 

https://github.com/apache/libcloud/commit/12b830889283ede2acf0d8a4ea874e755df33c9e

Merged with trunk and should be released with libcloud 0.14.0.