ONNX benchmarks

[filipecosta90]

Further references:

• Are there any performance/benchmark numbers available to share? microsoft/onnxruntime#133
• https://github.com/Microsoft/onnxruntime/tree/master/onnxruntime/test/perftest
• https://cloudblogs.microsoft.com/opensource/2020/01/21/microsoft-onnx-open-source-optimizations-transformer-inference-gpu-cpu/

[filipecosta90]

https://github.com/onnx/models/tree/master/vision/classification/mobilenet/model