title: Tensorflow predict grpc not working but RESTful API working fine
body: <p>When i am trying to execute below piece of client code i am getting error but succeeded when calling via RESTful API end point<br>
  <code>curl -d '{"signature_name":"predict_output","instances":[2.0,9.27]}' -X POST http://10.110.110.13:8501/v1/models/firstmodel:predict</code></p>
  
  <p>Could you please correct me in below code</p>
  
  <pre><code>import tensorflow as tf
  from tensorflow_serving.apis import predict_pb2
  from tensorflow_serving.apis import prediction_service_pb2_grpc
  import numpy as np
  import grpc
  server = '10.110.110.13:8501'
  channel = grpc.insecure_channel(server)
  stub = prediction_service_pb2_grpc.PredictionServiceStub(channel)
  request = predict_pb2.PredictRequest()
  request.model_spec.name = 'firstmodel'
  request.model_spec.signature_name = 'predict_output'
  request.inputs['input_x'].CopyFrom(tf.contrib.util.make_tensor_proto([12.0], shape=[1]))
  result_future = stub.Predict(request,40.)
  print(result_future.outputs['output_y'])
  </code></pre>
  
  <p>Got the below error message:</p>
  
  <pre><code>_Rendezvous: &lt;_Rendezvous of RPC that terminated with:
  status = StatusCode.UNAVAILABLE
  details = "Trying to connect an http1.x server"
  debug_error_string = "{"created":"@1545248014.367000000","description":"Error received from peer",
      "file":"src/core/lib/surface/call.cc","file_line":1083,"grpc_message":"Trying to connect an http1.x server","grpc_status":14}"
  </code></pre>
  
  <p>Below is the composed request information for your reference</p>
  
  <pre><code>model_spec {
    name: "firstmodel"
    signature_name: "predict_output"
  }
  inputs {
    key: "input_x"
    value {
      dtype: DT_FLOAT
      tensor_shape {
        dim {
          size: 1
        }
      }
      float_val: 12.0
    }
  }
  </code></pre>