Fixing vanilla_biometrics. We can run the first pca_atnt example without dask

bob/bio/base/__init__.py

bob/bio/base/config/examples/pca_atnt.py

...bio/base/pipelines/vanilla_biometrics/abstract_classes.py

bob/bio/base/pipelines/vanilla_biometrics/legacy.py

bob/bio/base/pipelines/vanilla_biometrics/mixins.py

bob/bio/base/script/vanilla_biometrics.py