Update vgg.py

Author: zsdonghao

tensorlayer/models/vgg.py

@@ -315,6 +315,8 @@ def vgg19(pretrained=False, end_with='outputs', mode='dynamic', name=None):
         restore_model(model, layer_type='vgg19')
     return model
 
+VGG16 = vgg16
+VGG19 = vgg19
 
 # models without pretrained parameters
 # def vgg11(pretrained=False, end_with='outputs'):