Update upload_regimen to pull from GitHub, to simplify the deployment process

[nicain]

Now that the repo is public, a regimen.yml file can be accessed without a password by the regimen upload script. Need to:

• [x] Update the script to read from github.
• [x] Add validation of script and md5
• [x] Validate transitions go to valid stages.
• [ ] Deprecate the stash repo.