Nda-tools

* [`nda-tools`] Removed password from settings.cfg and --password / -p flags.
* [`nda-tools`] Added keyring module for securely password storage and retrieval.
* [`vtcmd`] Fixed bug where 'Bad Credentials' error was displayed when trying to validate submissions containing manifest elements.

* [`nda-tools`] Updated logging mechanism from print statements to using the logging module.
* [`nda-tools`] fixed bug with resuming submission where the -wt flag was not having the intended effect.
* [`nda-tools`] removed obsolete DataManager classes and related logic.

* [`nda-tools`] Replaced calls to legacy Download Manager with calls to new package service.

* [`nda-tools`] Update password hashing to authenticate with NDA webservice endpoints.

* [`vtcmd`] Fixed bug that prevented resuming submissions when incomplete multipart uploads were present in s3 buckets.
* [`vtcmd`] Updated code to print current version of tool to console before running.

* [`vtcmd`] Added --skipValidation flag to skip checking that local associated files exist on filesystem.
* [`vtcmd`] New sections and options are automatically added to user settings.cfg.
* [`nda-tools`] Fixed bugs preventing use of full file paths on all operating systems.
* [`nda-tools`] Replaced use of aws_access_key and aws_secret_key with iam_user_credentials and data_manager_credentials, which defaults to use of FederationUser Token to submit from S3 objects if no credentials are supplied in settings.cfg.
* [`nda-tools`] Added unit tests for Utils.py for parse relative/full filepaths and automatically sanitizing paths based on path patterns.