add travis ci for paddle serving

python/examples/fit_a_line/test_client.py

 from paddle_serving_client import Client
-import paddle
 import sys
 
 client = Client()
 client.load_client_config(sys.argv[1])
 client.connect(["127.0.0.1:9393"])
 
+import paddle
 test_reader = paddle.batch(paddle.reader.shuffle(
     paddle.dataset.uci_housing.test(), buf_size=500), batch_size=1)