Merge pull request #27 from jonboulle/master

travis: bump go versions

.travis.yml

@@ -3,9 +3,9 @@ sudo: required
 dist: trusty
 
 go:
-  - 1.4
-  - 1.5.3
-  - 1.6
+  - 1.5.4
+  - 1.6.3
+  - 1.7
   - tip
 
 env: