1.Add a backbone: deitiii.
2.Add an optimizer: lamb.
3.Add a sampler: RASampler.
4.Add a lr update hook: CosineAnnealingWarmupByEpochLrUpdaterHook.
5.In easycv/models/classification/classification.py, I remove the default mixup_cfg to keep the classification.py clean.
* readthedocs build support
* change opencv version from 4.4.0.40 to 4.1.2.30
* update config file path with github url
* fix: clone AutoAugmentPolicy from torchvision error
* reorganize requirements file
* add model compression tutorial and cls modelzoo to readme.md
* add optional req