Agregando server de pruebas
Fixes ignoring init parameters. Better debug logging
offlinequeue is now a singleton
Agrega columnas al esquema
queued items are now marked as processing
Now failed processes are reenqueued up to maxAttempts times

 - if the result is HTTP status other than [200-299] reenqueue
 - if onProcess returns false, reenqueue
now can specify onFail function