Public scoreboard stopwatch feature

#10

app/views/contests/stopwatch.html.slim

@@ -0,0 +1,16 @@
+.row
+  .col
+    .alert.alert-primary
+      = t("contests.stopwatch.info")
+h1.mt-3 id="display-time" style="font-size: 80px;"
+= render "stopwatch_js"
+.row.mt-3
+  .col.d-flex
+    - if !@contest.start_time.present?
+      = button_to t("helpers.buttons.stopwatch_start"), "/contests/#{@contest.id}/stopwatch_start", method: :post, class: "btn btn-primary"
+    - if @contest.pause_time.present?
+      = button_to t("helpers.buttons.stopwatch_continue"), "/contests/#{@contest.id}/stopwatch_continue", method: :post, class: "btn btn-primary"
+    - if @contest.start_time.present? && !@contest.pause_time.present?
+      = button_to t("helpers.buttons.stopwatch_pause"), "/contests/#{@contest.id}/stopwatch_pause", method: :post, class: "btn btn-primary"
+    - if @contest.start_time.present?
+      = button_to t("helpers.buttons.stopwatch_reset"), "/contests/#{@contest.id}/stopwatch_reset", method: :post, class: "ms-3 btn btn-warning"