staging continuous deployment

It looks like http://staging.certificates.theodi.org/ is no longer deploying after the change from jenkins to travis.

I'm not totally familiar with the deployment details, but looking at [travis.yml](https://github.com/theodi/open-data-certificate/blob/master/.travis.yml#L5-L10) - it looks like this is only adding tags (`CURRENT`) when the master branch builds.

```yaml
after_success:
- ! '[ "$TRAVIS_BRANCH" == "master" ] && [ "$TRAVIS_PULL_REQUEST" == "false" ] &&
  curl -v -X DELETE -u $GITHUB_USER:$GITHUB_PASSWORD "https://api.github.com/repos/$TRAVIS_REPO_SLUG/git/refs/tags/CURRENT"'
- ! '[ "$TRAVIS_BRANCH" == "master" ] && [ "$TRAVIS_PULL_REQUEST" == "false" ] &&
  curl -v -X POST -d ''{"ref":"refs/tags/CURRENT","sha":"''$TRAVIS_COMMIT''"}''  --header
  "Content-Type:application/json" -u $GITHUB_USER:$GITHUB_PASSWORD "https://api.github.com/repos/$TRAVIS_REPO_SLUG/git/refs"'
```

If we were to copy these for the staging branch (with `STAGING` instead of `CURRENT`) would this be enough to get staging deployed again?