title: Add metadata to tensorflow frozen graph pb
body: <p>To share our trained tensorflow networks, we freeze the graph into a <code>.pb</code> file. We also create an xml file with some metadata such as the input tensors and output tensors, type of pre-processing to apply, training data information etc. The models are then served using Java or C# by loading the graph and evaluating the tensors etc.</p>
  
  <p>To make sharing easier, I would like to include this xml data somewhere in the <code>.pb</code> file. Is there any way to do this? One idea would be to have it as a tf.Constant, but I don't see how I could connect it to the normal graph.</p>
  
  <p>Note this is using <code>freeze_graph.py</code>. Is the new SavedModel format more suitable?</p>