places sidebar: Fix the sort function

When returning 1 for a pair (a,b), a sort function must
return -1 for the pair (b,a), otherwise things can go
badly.

https://bugzilla.gnome.org/show_bug.cgi?id=739729

gtk/gtkplacessidebar.c

@@ -3815,6 +3815,10 @@ places_sidebar_sort_func (GtkTreeModel *model,
     {
       retval = 1;
     }
+  else if (place_type_b == PLACES_CONNECT_TO_SERVER)
+    {
+      retval = -1;
+    }
 
   return retval;
 }