add ResNet18 pretrained

hubconf.py

 
 dependencies = ['paddle', 'numpy']
 
+import paddle
 
 from ppcls.modeling.architectures.resnet import ResNet18 as _ResNet18
 from ppcls.modeling.architectures.resnet import ResNet34 as _ResNet34
 from ppcls.modeling.architectures.resnet import ResNet50 as _ResNet50
 
 
+_checkpoints = {
+    'ResNet18': 'https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/ResNet18_pretrained.pdparams'
+}
+
+
 
 def ResNet18(**kwargs):
     '''ResNet18
     '''
+    pretrained = kwargs.pop('pretrained', False)
+
     model = _ResNet18(**kwargs)
+    if pretrained:
+        path = paddle.utils.download.get_weights_path_from_url(_checkpoints['ResNet18'])
+        model.set_state_dict(paddle.load(path))
+
     return model