changesets - fix notice type on successful promotion/deletion

This commit addresses the issue where the notices generated
for a successful promotion or deletion changeset was a
'sticky message'.

src/app/models/deletion_changeset.rb

@@ -75,7 +75,7 @@ def delete_content(notify = false)
 
     if notify
       message = _("Successfully deleted changeset '%s'.") % self.name
-      Notify.message message, :request_type => "changesets___delete"
+      Notify.success message, :request_type => "changesets___delete"
     end
 
   rescue Exception => e

src/app/models/promotion_changeset.rb

@@ -89,7 +89,7 @@ def promote_content(notify = false)
 
     if notify
       message = _("Successfully promoted changeset '%s'.") % self.name
-      Notify.message message, :request_type => "changesets___promote"
+      Notify.success message, :request_type => "changesets___promote"
     end
 
   rescue Exception => e