set go test timeout to 20m

Signed-off-by: 高汝彤 <rutong.grt@alibaba-inc.com>

.travis.yml

@@ -22,4 +22,4 @@ script:
   - go vet ./services/...
   - go build ./sdk
   - go build ./services/...
-  - go test -v ./integration/...
+  - go test -v  -timeout 20m ./integration/...