After the artifacts are generated and signed, you can run the following script under the folder tools, to upload them into the staging directory:
$ ./upload_artifacts.sh <WORK_DIR>
The <WORK_DIR> should be the same one used to download the source code. This script will create a remote directory named openwhisk-<major>-<minor> under the staging directory, and push all the files available locally under openwhisk-<major>-<minor> upstream. It will overwrite the old files or directories, if the directory openwhisk-<major>-<minor> is available as a svn folder.