Update bob/bio/face/extractor/__init__.py,...

Update bob/bio/face/extractor/__init__.py, bob/bio/face/test/test_extractors.py, bob/bio/face/embeddings/PyTorchModel.py files
Deleted bob/bio/face/extractor/MxNetModel.py, bob/bio/face/extractor/OpenCVModel.py, bob/bio/face/extractor/PyTorchModel.py, bob/bio/face/extractor/TensorFlowModel.py, bob/bio/face/config/baseline/opencv_tinyface_pipe.py, bob/bio/face/config/baseline/mxnet_tinyface_pipe.py files