API.
    *   Adding `drop_remainder` argument to `tf.data.Dataset.batch()` and
        `tf.data.Dataset.padded_batch()`, deprecating
        `tf.contrib.data.batch_and_drop_remainder()` and
        `tf.contrib.data.padded_batch_and_drop_remainder()`.
*   `tf.estimator`:
    *   `Estimator`s now use custom savers included in `EstimatorSpec` scaffolds