Launch the classifier training

[KristinaUlicna]

PR to enable GCN classifier training.

• [GCN] Rename model runs time stamp to save into folder chronologically
• [GCN] Rename val_fraction to train_fraction argument, which is what it is
• [GCN] Rename ignore_fraction to keep_patch_fraction argument, which is what it is
• [GCN] Extend hidden layers argument to list, e.g. [8, 16, 32, 64] - resolves [FEATURE REQUEST] Let GCN classifier accept a list of hidden layers #109
• [GCN] Write config hyperparameters documentation - resolves Add documentation #5
• [GCN] Add an example config file to illustrate how to write one.
• [GCN] Progress bar for image loading + feature extraction (tqdm) - resolves [FEATURE REQUEST] Logging report to GCN training #110

[mooniean]

LGTM.

With the extra instructions, it works. I tried training both a resnet152 and a resnet18 and both worked and trained.

[mooniean]

forgot to press approve

[chris-soelistyo]

Looks good! Just have a few comments

[quantumjot]

@chris-soelistyo - I would go ahead and merge this if you're happy with it