TensorFlow Model Optimization 0.3.0

This is the final release of TensorFlow Model Optimization 0.3.0.

Keras quantization API:

• This includes the initial release of the Keras quantization API.
• Tested against TensorFlow nightly

Keras pruning API:

• Features:
  • Added support for TensorFlowOpLayer
• Bugs Fixes:
  • Fixed edge case of propagating training=True to BatchNormalization layer when the arg is passed to call
    function instead of relying on tf.keras.backend.learning_phase().
  • Removed usage of _log_metrics API, which is no longer available in TF 2.2.0+.
• Tested against TensorFlow nightly, 1.14.0 and 2.0.0.