*   `tf.contrib.data.group_by_reducer()` is now available via the public
        API.
    *   `tf.contrib.data.choose_from_datasets()` is now available via the public
        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()`.