Use binary field for AgentSetting state

[janckerchen]

It is Hash field for state persistence at present. It's tedious to to_h/restore state with complex data structure which is normal in professional algo with many custom class defined.

suggestion is

#AgentSetting

 field :state, :type => Binary

#save state

setting.state = Marshal.dump(agent.state)

#restore state

agent.restore_state(Marshal.load(setting.state))

Then anything returned by agent.state can be persistence