MLP should do the actual JSON check

Todo was place-holder :)

Lines 406 to 412 in ab9c650

    
           //TODO 
        
           bool check_json(const nlohmann::json &j, const MLP &) { 
        
             return fluid::check_json(j, 
        
               {"layers"}, 
        
               {JSONTypes::ARRAY} 
        
             ); 
        
           }

https://discourse.flucoma.org/t/fluid-mlpregressor-not-returning-prediction-inside-collapsed-m4l-device/2259/9

	//TODO
	bool check_json(const nlohmann::json &j, const MLP &) {
	return fluid::check_json(j,
	{"layers"},
	{JSONTypes::ARRAY}
	);
	}