Official v1.1.0 Release - PyTorch GPU DDP Pretraining & Cleanup

Upgrades to PyTorch 2.0 and provides native DistributedDataParallel GPU Pretraining (1+ GPUs) for all models. Fully documented and cleaned up preprocessing flow (raw Something-Something-v2 data --> pretrained models).

Key Examples:

• General Overview of Preprocessing/Pretraining for Sth-Sth-v2: examples/pretrain/README.md
• PyTorch DDP Pretraining Script (invoke via torchrun): examples/pretrain/pretrain.py

What's Changed

• Release 1.1.0 - Native GPU/DDP Pretraining by @siddk in #14

Full Changelog: v1.0.0...v1.1.0