* Add a weighted choice option for RandAugment
* Adjust magnitude noise/std naming, config

Map pretrained checkpoint to cpu to avoid issue with some pretrained checkpoints still having CUDA tensors. Fixes #42

Add Res2net and DLA models. Update sotabench.

Add AutoAugment ImageNet policies for training

More optimizer work

Optimizers and more

Add RAdam, NovoGrad, Lookahead, and AdamW optimizers, a few ResNet tweaks and scheduler factory tweak.
* Add some of the trendy new optimizers. Decent results but not clearly better than the standards.
* Can create a None scheduler for constant LR
* ResNet defaults to zero_init of last BN in residual
* add resnet50d config

MixNet-XL

Add support to split random erasing blocks into randomly selected number with --recount arg. Fix random selection of aspect ratios.

Port Gluon Aligned Xception models