Updated Cloud Files examples

This PR updates the Rackspace Cloud Files examples to use the updated 1.7.3 APIs/release.

`SmokeTest` was run against the examples.
These examples run as part of a larger nightly [SmokeTest](https://github.com/jclouds/jclouds-examples/blob/master/rackspace/src/main/java/org/jclouds/examples/rackspace/SmokeTest.java) to ensure the examples are always in good working condition. I don't want the whole SmokeTest to die just because one example failed.