Fix unit tests.

Not sure why Jenkins didn't notice these were broken, but it didn't.

Change-Id: I3d6fcdca8430a1f34d9829ad6a1eda704805ee55
Put X-Timestamp in object 404 responses

This way the container reconciler can tell (sometimes) that an object
was deleted at a certain time.

Change-Id: I3a56f2367585803b82f0b254946896c34746f9ca