Merge pull request #78 from sergi/support-1.7-and-1.8

Switch to Go 1.7 and 1.8
diff --git a/.travis.yml b/.travis.yml
index a767fd5..4a22ed3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,8 @@
   - osx
 
 go:
-  - 1.6.x
   - 1.7.x
+  - 1.8.x
 
 sudo: false