title: Redis notifications: Get key and value on expiration
body: <p>we have the following use case: Every time a certain key expires, we need to get notified and do something, based on it's value. But when redis fires the <code>expired</code> event, the key was already removed from the db when we try to access it later on, which is expected of course.</p>
  
  <p>Now is there a way to access the entry again, after it expired? I guess not.</p>
  
  <p>So second option: Is there a way to tell redis to publish the whole value object instead of just the key when sending those events? I guess it could be added through Lua, but I'd interested in an easier option, if possible. We also need this behaviour for other events, we basically need all notifications to publish the value, not the key (we could do a <code>GET</code> once the event was received, but we want to get around the second call, primarily to have an atomic process, since the value could have changed between publishing the event and doing the <code>GET</code> to retrieve the value).</p>
  
  <p>Hope it's understandable. Maybe we can't see the obvious, so thanks in advance!</p>