(This is a merge of http://go/wvgerrit/14051) Adds support for passing a special provisioning response ("delete") to the provisioning API in order to unprovision the current origin. Note that the origin MUST be set or else this will fail. The existing, system-only unprovisionDevice() method is unaffected. Bug: 12247651 Change-Id: I16d296397d8e9e73c8f43e36c86838873318a398