Unifying imports, attempt to fix sphinx

bob/learn/tensorflow/analyzers/ExperimentAnalizer.py

bob/learn/tensorflow/datashuffler/Base.py

bob/learn/tensorflow/datashuffler/Disk.py

bob/learn/tensorflow/datashuffler/Memory.py

bob/learn/tensorflow/datashuffler/OnlineSampling.py

bob/learn/tensorflow/datashuffler/SiameseDisk.py

bob/learn/tensorflow/datashuffler/SiameseMemory.py

bob/learn/tensorflow/datashuffler/TripletDisk.py

bob/learn/tensorflow/datashuffler/TripletMemory.py

...n/tensorflow/datashuffler/TripletWithFastSelectionDisk.py

...learn/tensorflow/datashuffler/TripletWithSelectionDisk.py

...arn/tensorflow/datashuffler/TripletWithSelectionMemory.py

bob/learn/tensorflow/datashuffler/__init__.py

bob/learn/tensorflow/trainers/Trainer.py

bob/learn/tensorflow/trainers/TrainerSeq.py

bob/learn/tensorflow/trainers/__init__.py