Have TC auto-generate and use an auth token after initial NAS connect

Migrate TC to automatically registering and using an authentication token for the NAS connect instead of saving the root user password for the NAS.

Issues to be aware of:
1. Need to generate and/or allow the user to set a custom "hostname" for TrueCommand instance. This will be used to name the NAS auth token, so a NAS admin later can find/manage the TC access as needed.

2. Need to be careful about the situation where multiple TC systems are monitoring the same NAS. Prevent token naming conflicts and such.