support go1.12

Author: appleboy

.travis.yml

@@ -7,13 +7,16 @@ go:
   - 1.9.x
   - 1.10.x
   - 1.11.x
+  - 1.12.x
   - tip
 
 matrix:
   fast_finish: true
   include:
   - go: 1.11.x
     env: GO111MODULE=on
+  - go: 1.12.x
+    env: GO111MODULE=on
 
 install:
   - go get -d -t -v ./...