Public scoreboard stopwatch feature

#10

app/views/contests/scoreboard.html.slim

@@ -3,12 +3,16 @@ css:
     .mobile-single { display: block !important; }
     .desktop-single { display: none; }
     #scoreboard-switches { display: none; }
+    .stopwatch { font-size: 50px !important; }
   }
 
 - if @contest.puzzles.size < 2
   = render "selectors"
 
   turbo-frame id="scoreboard"
+    - if @contest.show_stopwatch
+      .stopwatch id="display-time" style="font-size: 60px; font-weight: 400; margin-bottom: 0; text-align: center;"
+      = render "stopwatch_js"
     a.btn.btn-primary href="" id="refresh-button" style="display: none;"
     .mobile-single style="display: none;"
       = render "scoreboard_mobile_single"