Bug: 7280093 User serial number was not being bumped up from 0 on a freshly wiped device due to the userlist not existing. This was resulting in the first 2 users getting the same serial number, messing up C2DM message delivery. This issue doesn't show up if you boot the device before adding a user, so it wasn't discovered earlier. Change-Id: I8a5d99b9ad2ccfb66a16cacac9548ba53f0be387