Feat/show fav rt lists on hover

Separated the small user list popover to its own component from reactions, made use of it for favs and rts, simple as

src/components/user_list_popover/user_list_popover.js

@@ -7,6 +7,11 @@ const UserListPopover = {
   components: {
     Popover: () => import('../popover/popover.vue'),
     UserAvatar: () => import('../user_avatar/user_avatar.vue')
+  },
+  computed: {
+    usersCapped () {
+      return this.users.slice(0, 16)
+    }
   }
 }