add sts test environment

.travis.yml

@@ -8,6 +8,8 @@ install:
 - go get golang.org/x/tools/cmd/cover
 - go get github.com/mattn/goveralls
 - go get gopkg.in/check.v1
+- go get github.com/satori/go.uuid
+- go get github.com/baiyubin/aliyun-sts-go-sdk/sts
 script:
 - cd oss
 - travis_wait 30 go test -v -covermode=count -coverprofile=coverage.out -timeout=30m