Adds support for Rackspace Cloud Files UK provider

This PR adds support for the multi-region based Rackspace Cloud Files UK Provider.

JIRA: 
https://issues.apache.org/jira/browse/JCLOUDS-423
https://issues.apache.org/jira/browse/JCLOUDS-299

Additions:
- Support for the Rackspace Cloud Files UK Provider.

Command to run live tests with the multi-region rackspace-cloudfiles-uk provider:
mvn clean install -Plive -Dtest.rackspace-uk.identity="username" -Dtest.rackspace-uk.credential="apiKey"

Tested against the Rackspace Cloud Files UK region.