Add license boilerplate to source files
diff --git a/src/ident.rs b/src/ident.rs
index bba6e1c..2f4be82 100644
--- a/src/ident.rs
+++ b/src/ident.rs
@@ -1,3 +1,11 @@
+// Copyright 2018 Syn Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
use std::borrow::Cow;
use std::cmp::Ordering;
use std::fmt::{self, Display};