Accept parameters on initial user creation

[deefdragon]

I'm currently working to create a helm template to create a postal deployment in Kubernetes, but the one step I cant seem to automate is the creation of the root user. This appears to require user interaction and is un-scriptable. While its not impossible to just tell the user to remote in and run the required script, it would be much more desirable to be able to set the username/password to run an init user script via args.