Refactoring JSON serialization of response object

    Swapping DRY code jsonutils.loads(webob.TestResponse.body) with
    webob.TestResponse.json_body property.

Change-Id: I2f4e0cd3f1f8abc209e19491287f3630b1c4e80d
Closes-Bug: #1304967
Merge "Refactoring JSON serialization of response object"