added benchmarks

claims.go

@@ -76,3 +76,12 @@ func (c Claims) Set(key string, v interface{}) {
 func (c Claims) Delete(key string) {
 	delete(c, key)
 }
+
+// Copy returns a new Claims map
+func (c Claims) Copy() (n Claims) {
+	n = make(Claims)
+	for k, v := range c {
+		n[k] = v
+	}
+	return
+}