* Added adafactor
* Added Adafactor and ran pre-commit
* modified operations
* Added docstrings
* Switched two ops to fix a bug
* added underscore for internal functions and removed the plus sign in the last return statment
* Removed parameter rms from the optimizer state because its not needed
* Added simple MNIST test for Adafactor and temporary training log
* remove test files
* nits in docs
* comment nit
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Co-authored-by: Awni Hannun <awni@apple.com>