message: Fix spelling in error message
diff: @@ -329,7 +329,7 @@ class Estimator(object):
  run_config.TaskType.PS):
  raise ValueError(
  'Train has been called wrong configuration. Please use '
  - 'tf.estimator.train_and_evaluate which calls propper API according '
  + 'tf.estimator.train_and_evaluate which calls proper API according '
  'to given configuration. Current configuration: {}.'.format(
  self.config))
  