[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

python/fastdeploy/serving/utils.py

@@ -0,0 +1,40 @@
+# coding:utf-8
+# Copyright (c) 2022  PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import contextlib
+import base64
+import numpy as np
+import cv2
+
+
+@contextlib.contextmanager
+def lock_predictor(lock):
+    lock.acquire()
+    try:
+        yield
+    finally:
+        lock.release()
+
+
+def cv2_to_base64(image):
+    data = cv2.imencode('.jpg', image)[1]
+    return base64.b64encode(data.tobytes()).decode('utf8')
+
+
+def base64_to_cv2(b64str):
+    data = base64.b64decode(b64str.encode('utf8'))
+    data = np.fromstring(data, np.uint8)
+    data = cv2.imdecode(data, cv2.IMREAD_COLOR)
+    return data