(Terry) Tang, Yuxin Wu, Ziyue(Louis) Lu

# Release 1.7.0

## Major Features And Improvements

*   Eager mode is moving out of contrib, try `tf.enable_eager_execution()`.
*   Graph rewrites emulating fixed-point quantization compatible with TensorFlow
    Lite, supported by new `tf.contrib.quantize` package.
*   Easily customize gradient computation with `tf.custom_gradient`.