As of July 16th 2015, this client has been updated to use JSON requests ONLY. All XML references have been removed at this time. Several new updates have been introduced:
Note that on July 20, 2015, Rackspace (in following with OpenStack developments) will disable XML support within the Cloud Servers API. All PowerClient users should upgrade to the new release. See the following for more information:
https://github.com/drmmarsunited/rackspacecloud_powershell/wiki