Fix for disabling debug mode for an application.

Currently it is not possible to turn off debug between cf and the cloud controller.

Since the api specs are not clear in this area I'm assuming in this patch that cloud controller is functioning correctly and that cf is wrong.  I've submitted a pull request to the cloud controller to test this api. https://github.com/cloudfoundry/cloud_controller_ng/pull/67

This is to fix cf so that it complies with the api cloud controller providing.