sandbox: switch to dynamic UUIDs

Migrate sandbox over to generating it's capsule update image GUIDs
dynamically from the namespace and board/image info. Update the
reference and tests to use the new GUIDs.

Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
9 files changed