Added Travis CI badge

Signed-off-by: Steve Winslow <swinslow@gmail.com>
diff --git a/README.md b/README.md
index b534443..c4fbd75 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
+[![Build Status](https://travis-ci.org/swinslow/spdx-go.svg?branch=master)](https://travis-ci.org/swinslow/spdx-go)
+
 SPDX-License-Identifier: CC-BY-4.0
 
 # spdx-go