Nda-tools

* [`nda-tools`] Username is now case-insensitive.
* [`nda-tools`] added --log-dir command line arg to configure location of generated log file
* [`vtcmd`] added validation for dataset description
* [`vtcmd`] updated error handling when structure missing from data-expected
* [`vtcmd`] code refactor to reduce memory footprint when handling large submissions. scroll through associated files instead of requesting credentials all up front

* [`nda-tools`] Added --verbose parser option. Enables debug logging.
* [`nda-tools`] Removed obsolete --password and -qa as parser option.
* [`downloadcmd`] Updated the package-metadata file naming conventions to be unique per package to avoid name collisions.
* [`downloadcmd`] Updated the logic to regenerate credentials if they expire.
* [`downloadcmd`] Fixed regression in s3 bucket download functionality.

* [`vtcmd`] updated logic to allow alt-endpoints to contain sub-folders
* [`downloadcmd`] Added validation for -dp arg

* [`vtcmd`] fixed regression affecting the -rs functionality
* [`nda-tools`] Added additional logging for network requests

* [`downloadcmd`] removed obsolete -r flag
* [`downloadcmd`] updated logic to request pre-signed urls in batches of 50 at a time
* [`downloadcmd`] updated logic to allow the program to pick up where it left off after an unexpected termination by parsing download-logs
* [`vtcmd`] added --validation-timeout parameter to allow timeouts >5min for validation (useful for large csv's)

* [`vtcmd`] added -rs feature to allow users to fix QA errors.