新增go modules支持，自行管理第三方包依赖，方便开发者使用

third/github.com/fatih/structs/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+go: 
+ - 1.7.x
+ - 1.8.x
+ - 1.9.x
+ - tip
+sudo: false
+before_install:
+- go get github.com/axw/gocov/gocov
+- go get github.com/mattn/goveralls
+- if ! go get github.com/golang/tools/cmd/cover; then go get golang.org/x/tools/cmd/cover; fi
+script:
+- $HOME/gopath/bin/goveralls -service=travis-ci