services/tidyable: new tidyable service interface

This CL introduces a new Tidyable interface for services that maintain
reclaimable state.

Change-Id: Ia5e2ecb45b1d6d90c955e57326f4669f01ee1348
MultiPart: 2/2
diff --git a/services/application/applicationd/service.go b/services/application/applicationd/service.go
index 03f9139..e99a7a4 100644
--- a/services/application/applicationd/service.go
+++ b/services/application/applicationd/service.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"fmt"
 	"sort"
 	"strings"
 
@@ -333,3 +334,7 @@
 	}
 	return nil
 }
+
+func (i *appRepoService) TidyNow(ctx *context.T, call rpc.ServerCall) error {
+	return fmt.Errorf("method not implemented")
+}