On sign out right after push, the pushed objects don't trigger change events when signed in again

to reproduce

```js
// end session (forces unauthenticated state)
$.ajax({type: 'DELETE', url:'/_api/_session'})

// add new object
hoodie.store.add('test', {})

// reauthenticate then sign out. account.signOut pushes local changes before ending session
hoodie.account.signIn(username, password, {silent: true}).done( hoodie.account.signOut )

// sign back in
hoodie.account.signIn(username, password)

// the "test" object is in the /_changes response, but not in local Storage
hoodie.store.findAll('test').done( function(objects) { alert(objects.length)})
```