Instantiate native contract

[kvinwang]

The PR implement native contract instantiation.

[h4x3rotab]

What's the return value?

[kvinwang]

        loop {
            match self.process_next_message(block) {
                Err(err) => {
                    error!("Error processing message: {:?}", err);
                }
                Ok(no_more) => {
                    if no_more {
                        break;
                    }
                }
            }
        }