because they have too many HTML elements embedded

The upgrade progress picks up the actual output of the command line
firmware tools, which expects monospaced output in order to be fully
readable and aligned.  Looks a bit archaic, but not worse than before.

This avoids akward scenarios when the webserver is reloading,
spitting out temporary messages.  In that case, simply keep
polling until the request is back.  The backend keeps running
anyway.

This reverts commit 7030a38a.
Avoids a warning on bootup when done.  It may throw people off.