fix image reader and imagenet doc

python/examples/imagenet/README.md

@@ -44,6 +44,6 @@ python -m paddle_serving_server_gpu.serve --model ResNet50_vd_model --port 9696
 
 client send inference request
 ```
-python image_rpc_client.py ResNet50_vd_client_config/serving_client_conf.prototxt
+python resnet50_rpc_client.py ResNet50_vd_client_config/serving_client_conf.prototxt
 ```
 *the port of server side in this example is 9696

python/examples/imagenet/README_CN.md

@@ -44,6 +44,6 @@ python -m paddle_serving_server_gpu.serve --model ResNet50_vd_model --port 9696
 
 client端进行预测
 ```
-python image_rpc_client.py ResNet50_vd_client_config/serving_client_conf.prototxt
+python resnet50_rpc_client.py ResNet50_vd_client_config/serving_client_conf.prototxt
 ```
 *server端示例中服务端口为9696端口

python/paddle_serving_app/reader/image_reader.py

@@ -13,14 +13,19 @@
 # limitations under the License.
 import cv2
 import os
-import urllib
 import numpy as np
 import base64
+import sys
 from . import functional as F
 from PIL import Image, ImageDraw
 import json
 
 _cv2_interpolation_to_str = {cv2.INTER_LINEAR: "cv2.INTER_LINEAR", None: "None"}
+py_version = sys.version_info[0]
+if py_version == 2:
+    import urllib
+else:
+    import urllib.request as urllib
 
 
 def generate_colormap(num_classes):