fix weight and init_score assignment in lgb.cv (#1040)
fix weight and init_score assignment in lgb.cv (#1040)


microsoft/LightGBM,Laurae2/LightGBM,microsoft/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,Laurae2/LightGBM,microsoft/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,Laurae2/LightGBM