The contest logging page doesn't have resubmission avoidance so users could click
the save button multiple times and get duplicated QSOs. What's more, this happends
more commonly in contest because of the high pace.
The fix was borrowed from the implimentation in `assets/js/sections/qso.js'.
Ref: e4d17a2a07/assets/js/sections/qso.js (L158)
However, this looks great but could be annoying for slow servers. It could also
be implemented by blanking the qso info earlier so that the user wouldn't be
able to click again. But this may trick users to think the QSO was already uploaded
when it really isn't.
Signed-off-by: William Goodspeed <goodspeed@anche.no>
c3e76e67a8