Move dummy service implementations into their own package.

go/src/infra/gae/libs/gae/dummy/doc.go

Index: go/src/infra/gae/libs/gae/dummy/doc.go
diff --git a/go/src/infra/gae/libs/gae/dummy/doc.go b/go/src/infra/gae/libs/gae/dummy/doc.go
new file mode 100644
index 0000000000000000000000000000000000000000..426727e8210fb02ad8b2c92cdc4b5e95c6700c6d
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/dummy/doc.go
@@ -0,0 +1,20 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package dummy comtains dummy implementations of:
+//   * gae.RawDatastore
+//   * gae.Memcache
+//   * gae.TaskQueue
+//   * gae.GlobalInfo
+//   * gae.DSQuery
+//
+// These dummy implementations panic with an appropriate error message when
+// any of their methods are called. The message looks something like:
+//   dummy: method Interface.Method is not implemented
+//
+// The dummy implementations are useful when implementing the interfaces
+// themselves, or when implementing filters, since it allows your stub
+// implementation to embed the dummy version and then just implement the methods
+// that you care about.
+package dummy