* disable speed perturbation by default
* minor fixes
* minor updates
* updated bash scripts to incorporate with the `speed-perturb` arg
* minor fixes
1. changed the naming scheme from `speed-perturb` to `perturb-speed` to align with the librispeech recipe
>> 00256a7669/egs/librispeech/ASR/local/compute_fbank_librispeech.py (L65)
2. changed arg type for `perturb-speed` to str2bool
* Use jsonl for cutsets in the librispeech recipe.
* Use lazy cutset for all recipes.
* More fixes to use lazy CutSet.
* Remove force=True from logging to support Python < 3.8
* Minor fixes.
* Fix style issues.
* Add modified transducer for aishell.
* Minor fixes.
* Add extra data in transducer training.
The extra data is from http://www.openslr.org/62/
* Update export.py and pretrained.py
* Update CI to install pretrained models with aishell.
* Update results.
* Update results.
* Update README.
* Use symlinks to avoid copies.
