UX: user preferences allows users to choose which title to use from their badges and groups

lib/guardian.rb

@@ -215,8 +215,11 @@ class Guardian
     can_administer?(user) && !user.moderator?
   end
 
-  def can_grant_title?(user)
-    user && is_staff?
+  def can_grant_title?(user, title = nil)
+    return true if user && is_staff?
+    return false if user != @user
+    return true if user.badges.where(name: title, allow_title: true).exists?
+    user.groups.where(title: title).exists?
   end
 
   def can_change_primary_group?(user)