Test only code in master on Travis.

.travis.yml

@@ -13,6 +13,10 @@ otp_release:
   - R16B02
   - R16B01
 
+branches:
+  only:
+    - master
+
 before_install:
   - wget https://s3.amazonaws.com/rebar3/rebar3
   - chmod +x rebar3