[Serving] Add a simple Python serving (#962)

* init simple serving

* simple serving is working

* ppyoloe demo

* Update README_CN.md

* update readme

* complete vision result to json

examples/vision/detection/paddledetection/python/serving/client.py

@@ -0,0 +1,28 @@
+import requests
+import json
+import cv2
+import base64
+import fastdeploy as fd
+
+if __name__ == '__main__':
+    url = "http://127.0.0.1:8000/fd/ppyoloe"
+    headers = {"Content-Type": "application/json"}
+
+    im = cv2.imread("000000014439.jpg")
+    data = {
+        "data": {
+            "image": fd.serving.utils.cv2_to_base64(im)
+        },
+        "parameters": {}
+    }
+
+    resp = requests.post(url=url, headers=headers, data=json.dumps(data))
+    if resp.status_code == 200:
+        r_json = json.loads(resp.json()["result"])
+        det_result = fd.vision.utils.json_to_detection(r_json)
+        vis_im = fd.vision.vis_detection(im, det_result, score_threshold=0.5)
+        cv2.imwrite("visualized_result.jpg", vis_im)
+        print("Visualized result save in ./visualized_result.jpg")
+    else:
+        print("Error code:", resp.status_code)
+        print(resp.text)