add allowsRotation to gamepad

[finscn]

Users could set gamepad.allowsRotation by themselves as same as exitOnMenuPress.

example:

    var gamepads = navigator.getGamepads();
    var gamepad = gamepads[1] || gamepads[0];
    if (!gamepad) {
        // console.log('No Gamepads connected');
        return;
    }

    gamepad.allowsRotation = true;

I think in Game , allowsRotation =true is more useful ,so default value is true.