Automatically add robots.txt

When deploying a dev/test bucket, add a robots.txt to tell google to crawl none. 
```
User-agent: *
Disallow: /
```

When deploying a production bucket change robots.txt to:
```
User-agent: *
Allow: /
```

Only add a robots.txt file if one doesnt already exist.

Add a in the upload method that will allow/disallow user agents depending if its prod/test