title: Automatically create a new object from GridSearchCV best_params_
body: <p>Assume I want to fit a random forest, <code>RFC</code>, and grid search using sklearns <code>GridSearchCV</code>.
  We can get the best parameters using <code>RFC.best_params_</code> but if I then want to create a random forest I need manually to write those parameters in e.g <code>RFC(n_estimators=12,max_depth=7)</code> afterwards. Is there a way,something like <code>RFC_opt=RFC(best_params_)</code> to do it automatically?</p>