Normalize the object in `create_or_bump_for` only after ensuring the activity type is Create

Fixes #874 (closed)

The problem was that if an object that is an activity (e.g Undo has Follow as an object) is normalized, it will not find it in the objects table and instead try to fetch it. Fetching via AP will fail because Transmogrifier does not handle Creates with activity types as objects, so it will fallback to OStatus, which will handle it as a new follow activity, thus following the user again