Checkpoint the scores with pickle and attached the score writer to the pipeline

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

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

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

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

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

bob/bio/base/test/test_vanilla_biometrics.py