Add serializers to scheduler call

 * For some purposes, we should able to pass typed
   object as one of method arguments to Scheduler.
   For doing that, we pass serializer for this argument -
   it will be serialized during save to the DB and
   will be deserialized during delayed method call.

Change-Id: I5b4f4f3638d09888b331c29bba9c095163d62288