FEATURE: Flag count in post menu

This change shows a notification number besides the flag icon in the
post menu if there is reviewable content associated with the post.
Additionally, if there is pending stuff to review, the icon has a red
background.

We have also removed the list of links below a post with the flag
status. A reviewer is meant to click the number beside the flag icon to
view the flags. As a consequence of losing those links, we've removed
the ability to undo or ignore flags below a post.

config/site_settings.yml

@@ -190,10 +190,9 @@ basic:
   post_menu:
     client: true
     type: list
-    default: "like-count|like|share|flag|edit|bookmark|delete|admin|reply"
+    default: "like|share|flag|edit|bookmark|delete|admin|reply"
     allow_any: false
     choices:
-      - like-count
       - like
       - edit
       - flag