GitLab

- TorchScript-able `Wav2Vec2Model` class
- Factory functions for three configurations presented in the paper 
  - `wav2vec2_base`
  - `wav2vec2_large`
  - `wav2vec2_large_lv60k`

Co-authored-by: Vincent Quenneville-Belair <vincentqb@gmail.com>

Co-authored-by: Ji Chen <jimchen90@devfair0160.h2.fair>

* add wav2letter model

* add unit_test to model

* add docstrings

* add documentation

* fix minor error, change logic on forward

* update padding same with ceil

* add inline typing and minor fixes to docstrings

* remove python2

* add formula do docstrings, change param name

* add test with mfcc, add pytest

* fix bug, update docstrings

* change parameter name