Merge pull request #83 from sergi/support-go-1.9

Support Go 1.9 and remove 1.7
diff --git a/.travis.yml b/.travis.yml
index 4a22ed3..85868de 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,8 @@
   - osx
 
 go:
-  - 1.7.x
   - 1.8.x
+  - 1.9.x
 
 sudo: false