Changes

Replace all occurences of tf.contrib.estimator.BaselineEstimator with tf.estimator.BaselineEstimator
Replace all occurences of tf.contrib.estimator.DNNLinearCombinedEstimator with tf.estimator.DNNLinearCombinedEstimator
Replace all occurrences of tf.contrib.estimator.DNNEstimator with tf.estimator.DNNEstimator
Replace all occurrences of tf.contrib.estimator.LinearEstimator with tf.estimator.LinearEstimator
Users of tf.contrib.estimator.export_all_saved_models and related should switch to tf.estimator.Estimator.experimental_export_all_saved_models.
Update regression_head to head API for Canned Estimator V2.
Update multi_class_head to head API for Canned Estimator V2.
Replace all occurences of tf.contrib.estimator.InMemoryEvaluatorHook and tf.contrib.estimator.make_stop_at_checkpoint_step_hook with tf.estimator.experimental.InMemoryEvaluatorHook and tf.estimator.experimental.make_stop_at_checkpoint_step_hook
Migrate linear optimizer from contrib to core.

Thanks to our Contributors

This release contains contributions from many people at Google.