monitor page: error messages are not displaying when an error is encountered on the back end.

[Trek Hopton]

When an error is encountered such as issue #245, the Msg parameter in the template is not checked or used in monitor.html.

This results in users getting blank pages when an error is encountered with no error message to report to tech support or to help debug.

The message can be seen in the cloud logs but it should also be visible to the user on the web page.

This can be done by using our other pages like broadcast.html as an example, put this check somewhere in monitor.html:

{{if .Msg}}
      <div class="red">
        {{.Msg}}
      </div>
      <br>
    {{end}}

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