* For CIFAR-10 / ImageNet only
* Refactor data_loaders.py, reduce code duplication
* Implemented custom sampler
* Integrated in image classification sample
* Since we now shuffle the test set, had to update expected results
  in 2 full_flow_tests that do evaluation

* Support for multi-phase activations logging

Enable logging activation both durning training and validation at
the same session.

* Refactoring: Move parser to its own file

* Parser is moved from compress_classifier into its own file.
* Torch version check is moved to precede main() call.
* Move main definition to the top of the file.
* Modify parser choices to case-insensitive