*   Add `tf.contrib.bayesflow.metropolis_hastings`.
*   Add `log_rate` parameter to `tf.contrib.distributions.Poisson`.
*   Extend `tf.contrib.distributions.bijector` API to handle some non-injective
    transforms.
*   Java:
    *   Generics (e.g., `Tensor<Integer>`) for improved type-safety (courtesy
        @andrewcmyers).
    *   Support for multi-dimensional string tensors.