Improvements to user drafts (#6226)

* drafts in user profile: only show to user herself (not to admins), use avatar replying to (instead of topic OP), add keyboard shortcut for drafts, simplify display labels

* use JSON when testing Draft.stream

lib/guardian/user_guardian.rb

@@ -30,10 +30,6 @@ module UserGuardian
     is_me?(user) || is_admin?
   end
 
-  def can_see_drafts?(user)
-    is_me?(user) || is_admin?
-  end
-
   def can_silence_user?(user)
     user && is_staff? && not(user.staff?)
   end