code: function cliUpdateConfig (configDir, hostname, command) {
    cliUtil.fillEmptyServerCredentialsFromPrompt(command,
      function (error) {
        if (error) {
          provisionUtil.invokeCallback(error, command.doneCallback,
            command.verbosity)
        } else {
          updateConfig(configDir,
            cliUtil.pullHostInfoFromCommand(hostname, command),
            command)
        }
      }
    )
  }
docs: Action function invoked for the updateconfig subcommand.
  @param {String} configDir - Directory in which to store the private key
  and CSR file.
  @param {String} hostname - Name of the management service host.
  @param {Command} command - The Commander command to append options onto.