CheckRoot is a helper to return on PreRunE, so we can add it to commands that require root.

Execute adds all child commands to the root command and sets flags appropriately.

NewBuildDisk returns a new instance of the build-disk subcommand and appends it to the root command.

NewBuildISO returns a new instance of the buid-iso subcommand and appends it to the root command.

NewInstallCmd returns a new instance of the install subcommand and appends it to the root command.

NewUpgradeCmd returns a new instance of the upgrade subcommand and appends it to the root command.