add pruning

...3-pruning/.ipynb_checkpoints/exercise_30-checkpoint.ipynb

...3-pruning/.ipynb_checkpoints/exercise_31-checkpoint.ipynb

exercises/3-pruning/.ipynb_checkpoints/net-checkpoint.py

.../3-pruning/.ipynb_checkpoints/size_on_disk-checkpoint.png

exercises/3-pruning/__pycache__/net.cpython-36.pyc

exercises/3-pruning/__pycache__/utils.cpython-36.pyc

exercises/3-pruning/accuracy_l1.png

exercises/3-pruning/data/cifar-10-batches-py/batches.meta

exercises/3-pruning/data/cifar-10-batches-py/data_batch_1

exercises/3-pruning/data/cifar-10-batches-py/data_batch_2

exercises/3-pruning/data/cifar-10-batches-py/data_batch_3

exercises/3-pruning/data/cifar-10-batches-py/data_batch_4

exercises/3-pruning/data/cifar-10-batches-py/data_batch_5

exercises/3-pruning/data/cifar-10-batches-py/readme.html

exercises/3-pruning/data/cifar-10-batches-py/test_batch

exercises/3-pruning/exercise_30.ipynb

exercises/3-pruning/exercise_31.ipynb

exercises/3-pruning/size_on_disk.png