Add server/cache support to gaeconfig.

dm/api/template/loader.go

Index: dm/api/template/loader.go
diff --git a/dm/api/template/loader.go b/dm/api/template/loader.go
index af6b6b97aff1cce80ef92c37e8b4c90b56f0782b..3edf73501b87be4949e5bd1286d7e7985a7358ac 100644
--- a/dm/api/template/loader.go
+++ b/dm/api/template/loader.go
@@ -9,10 +9,10 @@ import (
 
 	"golang.org/x/net/context"
 
-	"github.com/luci/luci-go/common/config"
 	"github.com/luci/luci-go/common/data/text/templateproto"
-	"github.com/luci/luci-go/common/proto"
 	dm "github.com/luci/luci-go/dm/api/service/v1"
+	"github.com/luci/luci-go/server/config"
+	"github.com/luci/luci-go/server/config/textproto"
 )
 
 // LoadFile loads a File by configSet and path.
@@ -21,16 +21,13 @@ func LoadFile(c context.Context, project, ref string) (file *File, vers string,
 	if ref != "" {
 		cfgSet += "/" + ref
 	}
-	templateData, err := config.GetConfig(c, cfgSet, "dm/quest_templates.cfg", false)
-	if err != nil {
-		return
-	}
+
 	file = &File{}
-	vers = templateData.ContentHash
-	err = proto.UnmarshalTextML(templateData.Content, file)
-	if err != nil {
+	var meta config.Meta
+	if err = config.Get(c, config.AsService, cfgSet, "dm/quest_templates.cfg", textproto.Message(file), &meta); err != nil {
 		return
 	}
+	vers = meta.ContentHash
 	err = file.Normalize()
 	return
 }