add signatures to messages to avoid double processing

weed/pb/filer_pb/signature.go

@@ -0,0 +1,13 @@
+package filer_pb
+
+func (r *CreateEntryRequest) AddSignature(sig int32) {
+	r.Signatures = append(r.Signatures, sig)
+}
+func (r *CreateEntryRequest) HasSigned(sig int32) bool {
+	for _, s := range r.Signatures {
+		if s == sig {
+			return true
+		}
+	}
+	return false
+}