Update Travis for 1.9
diff --git a/.travis.yml b/.travis.yml
index 706ead4..c760d24 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,8 @@
 language: go
 
 go:
-    - 1.7
     - 1.8
+    - 1.9
     - tip
 
 script: