title: Dataflow template not using the runtime parameters
body: <p>I am using a dataflow template to run cloud dataflow</p>
  
  <p>I am providing some default values and calling template. Dataflow shows the pipeline options correctly in the dataflow pipeline summary. but it's not taking the runtime values.</p>
  
  <pre><code>class Mypipeoptions(PipelineOptions):
      @classmethod
      def _add_argparse_args(cls, parser):
          parser.add_value_provider_argument(
              '--preprocess_indir',
              help='GCS path of the data to be preprocessed',
              required=False,
              default='gs://default/dataset/'
          )
          parser.add_value_provider_argument(
              '--output_dir_train',
              help='GCS path of the preprocessed train data',
              required=False,
              default='gs://default/train/'
          )
          parser.add_value_provider_argument(
              '--output_dir_test',
              help='GCS path of the preprocessed test data',
              required=False,
              default='gs://default/test/'
          )
          parser.add_value_provider_argument(
              '--output_dir_validate',
              help='GCS path of the preprocessed validate data',
              required=False,
              default='gs://default/validate/'
          )
  </code></pre>
  
  <p>Then I am checking the values are accessible </p>
  
  <pre><code>p = beam.Pipeline(options=args)
  
      if args.preprocess_indir.is_accessible():
          input_dir = args.preprocess_indir
      else:
          input_dir = getValObj(args.preprocess_indir)
  
  
      if args.output_dir_train.is_accessible():
          output_train = args.output_dir_train
      else:
          output_train = getValObj(args.output_dir_train)
  
      if args.output_dir_test.is_accessible():
          output_test = args.output_dir_test
      else:
          output_test = getValObj(args.output_dir_test)
  
      if args.output_dir_validate.is_accessible():
          output_validate = args.output_dir_validate
      else:
          output_validate = getValObj(args.output_dir_validate)
  </code></pre>
  
  <p>Now when calling the template, I could see the values I wanted being passed as (Mypipeoptions)pipeine option parmater but its not used in the actual run, Instead using default options given</p>