Remove RestContext from Rackspace examples

This PR removes RestContext from the Rackspace examples as the first step towards the work to be done in [JCLOUDS-346](https://issues.apache.org/jira/browse/JCLOUDS-346).

Please refer to [JCLOUDS-152](https://issues.apache.org/jira/browse/JCLOUDS-152) which discusses the removal of RestContext.

Each updated example was debugged/tested against the Rackspace Cloud IAD region.

The logo link has also been updated post site-branding... Thx!