Add more recent Go versions.
diff --git a/.travis.yml b/.travis.yml
index bdcd986..946f98c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,8 @@
 go:
   - 1.1
   - 1.2
+  - 1.3
+  - 1.4
   - tip
 script: script/cibuild
 after_success: