Script to download commonvoice dataset
@SeanNaren when you commit, could you please do "git commit -s ..." to "sign" your commits.
For the already committed commits, DCO's bot output tells you https://github.com/NVIDIA/NeMo/pull/1361/checks?check_run_id=1321341664 how to sign already committed commits. 

The -s flag means: "certifies that committer has the rights to submit this work under the same license and agrees to a Developer Certificate of Origin (see http://developercertificate.org/ for more information)". We thought that asking for this is an easier ask then asking every external contributor to sign some sort of CLA.
 Will do! I think I made a mess with the DCO commands, will fix... @okuchaiev should all be done!
Ties to #568, it would be nice to have a script here to download common voice (and be language agnostic). The script works in a similar fashion to the librispeech script. Let me know if theres any issues. We have a blog post coming out where I had to format CV for NeMo :)