`sand rename` subcommand

[banksean]

From host: sand rename <existing sandbox name> <new sandbox name> should

• update the db (but leave the sandbox ID alone - just update name references)
• update git branches, git mirror, remotes etc on the host that refer to the old sandbox name
• update container system references to the old name
  • TODO: determine if container even supports this operation
  • may require multiple commands, e.g. stopping/exporting/removing/re-creating the container from exported data

From sanbox (innie): I think it's acceptable to leave this subcommand out of innie for now.