Adding travis ci config for go 1.7

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index e2a6a62..726c146 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,7 @@
 go:
   - 1.5
   - 1.6
+  - 1.7
   - tip
 
 # Setting sudo access to false will let Travis CI use containers rather than