Merge pull request #65 from terraform-providers/travis-go-modules

enable go modules and vendoring in travis

Author: appilon

.travis.yml

@@ -5,6 +5,8 @@ services:
 language: go
 go:
   - "1.11.x"
+env:
+  - GO111MODULE=on GOFLAGS=-mod=vendor
 
 install:
 # This script is used by the Travis build to install a cookie for