Pass-through post creation time when importing posts

model/post.go

@@ -120,7 +120,10 @@ func (o *Post) PreSave() {
 
 	o.OriginalId = ""
 
-	o.CreateAt = GetMillis()
+	if o.CreateAt == 0 {
+		o.CreateAt = GetMillis()
+	}
+
 	o.UpdateAt = o.CreateAt
 
 	if o.Props == nil {