Add go version upto 1.13.x for travis

Author: Saddam H

.travis.yml

@@ -7,7 +7,10 @@ matrix:
     - go: 1.7
     - go: 1.8
     - go: 1.9
-    - go: tip
+    - go: 1.10.x
+    - go: 1.11.x
+    - go: 1.12.x
+    - go: 1.13.x
   allow_failures:
     - go: tip
 before_install: