added metadata helper tool

Makefile

@@ -5,9 +5,11 @@ GCFLAGS=-gcflags '-e'
 LDFLAGS=-ldflags '-buildid=$(VERSION) -X main.version=$(VERSION) -s -w'
 PROGRAM=cachefs
 CMD=-o $(PROGRAM) cmd/$(PROGRAM)/main.go
+MD_PROGRAM=metadatagen
+MD_CMD=-o $(MD_PROGRAM) cmd/$(MD_PROGRAM)/main.go
 ENV=CGO_ENABLED=0 GO111MODULE=on
 
-all: $(PROGRAM)
+all: $(PROGRAM) $(MD_PROGRAM)
 
 setup:
 	$(CC) install github.com/client9/misspell/cmd/misspell@latest
@@ -25,6 +27,9 @@ vendor: clean gofmt
 $(PROGRAM): clean gofmt
 	$(ENV) $(CC) $(BUILD) $(GCFLAGS) $(LDFLAGS) $(CMD)
 
+$(MD_PROGRAM): clean gofmt
+	$(ENV) $(CC) $(BUILD) $(GCFLAGS) $(LDFLAGS) $(MD_CMD)
+
 clean:
 	$(CC) clean -x