Add a fallback for Safari copy-to-clipboard

Also, hide the tooltip in a less stupid way.

Closes #3547

app/assets/javascripts/copy_to_clipboard.js.coffee

@@ -9,13 +9,24 @@ $ ->
   clipboard.on 'success', (e) ->
     $(e.trigger).
       tooltip(trigger: 'manual', placement: 'auto bottom', title: 'Copied!').
-      tooltip('show')
+      tooltip('show').
+      one('mouseleave', -> $(this).tooltip('hide'))
     # Clear the selection and blur the trigger so it loses its border
     e.clearSelection()
     $(e.trigger).blur()
-    # Manually hide the tooltip after 1 second
-    setTimeout(->
-      $(e.trigger).tooltip('hide')
-    , 1000)
+  # Safari doesn't support `execCommand`, so instead we inform the user to
+  # copy manually.
+  #
+  # See http://clipboardjs.com/#browser-support
+  clipboard.on 'error', (e) ->
+    if /Mac/i.test(navigator.userAgent)
+      title = "Press ⌘-C to copy"
+    else
+      title = "Press Ctrl-C to copy"
+
+    $(e.trigger).
+      tooltip(trigger: 'manual', placement: 'auto bottom', html: true, title: title).
+      tooltip('show').
+      one('mouseleave', -> $(this).tooltip('hide'))