[milo] remove unused code.

milo/appengine/model/settings.go

Index: milo/appengine/model/settings.go
diff --git a/milo/appengine/model/settings.go b/milo/appengine/model/settings.go
deleted file mode 100644
index cfa2d49bf78becab147da04a22aac15fedd1c7bb..0000000000000000000000000000000000000000
--- a/milo/appengine/model/settings.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2015 The LUCI Authors. All rights reserved.
-// Use of this source code is governed under the Apache License, Version 2.0
-// that can be found in the LICENSE file.
-
-package model
-
-import "github.com/luci/luci-go/server/auth/identity"
-
-// UserConfig keys off of an identity and stores user configuration.
-type UserConfig struct {
-	UserID identity.Identity `gae:"$id"`
-	Theme  string
-}