Support for multi-signature models in RunInference API

[codesue]

Is it possible to use the RunInference API with models that have more than one signature? I used the RunInference API via the TFX BulkInferrer component with a model that has two signatures and got the error ValueError('Signature should have 1 and only 1 inputs'). I stopped getting the error after removing one of the signatures from my model.