Stats and achievements waiting to be saved will now be used during stat/achievement retrieval
Completed UUID update
* UUID can now be looked up in the database. 
  NOTE: The name field is not indexed nor guaranteed to be unique.
  This should only be used for offline players if you dont want to use the mojang lookup
* Name->UUID map is now cleared after migration (it may be quite large depending on the server)
* Last known player name is now updated if needed
* Fixed NPE in StatRetrieverTask (forgot to set a var)