SqeezeNet meta data for create_cnn function

[devforfu]

Based on forum's discussion, the PR makes an attempt to bring the support of SqeezeNet architecture into the library. Now you're able to use the architecture like ResNets:

learn = create_cnn(data, models.squeezenet1_1)

However, I've chosen the layers groups split quite arbitrary (splitting model on maxpool layers) so would be glad to see your comments if there is a better configuration.

[sgugger]

Thanks!
Concerning your tests, please leave the full training only for one integration test with the simple CNN. Tests are also run on CPU and we can't have too many that are to slow (so only one training per application).

[sgugger]

Please amend your PR to be able to merge with the latest big refactor. If it's easiest, close this one and reopen another.

[devforfu]

Ok, sure, will do.

[devforfu]

@sgugger Removed all training from the tests except one place with simple_cnn and merged with the most recent master. Now should be better.

[devforfu]

Seems there is a bug in tests, going to fix soon.

[devforfu]

@sgugger Seems like there is a timeout issue, however, I don't train any model in the tests I've added. Do you think it is worth to change something in the tests to decrease CI execution time?

[devforfu]

I've tried to address the issues. I think now the create_cnn should look better. How do you think, should we change anything else? Are these changes are still relevant to the library? Also, I've included the following test:

@pytest.mark.slow
@pytest.mark.parametrize('arch', [models.resnet18, models.squeezenet1_1])
def test_models_meta(mnist_tiny, arch, zero_image):
    learn = create_cnn(mnist_tiny, arch, metrics=[accuracy, error_rate])
    pred = learn.predict(zero_image)
    assert pred is not None

Note the last line. I am not really sure what to assert here so I am just making sure that the output is not None. The main goal of this test is to make sure that architectures are instantiated correctly. Actually, the test has passed if we just don't get any exception so it could be assert True as well.

[sgugger]

Seems good, thanks!