Add setting flag to issue a 301 redirect instead of returning the

This lets nginx take the request and host the file.

nginx config to highjack the request and server the package, the htpasswd file should be in sync with localshop credentials.

```
  location /source {
    # Have nginx host the file, not the gunicorn process.
    root /home/vbabiy/Projects/git-projects/localshop/;

    auth_basic "Localshop";
    auth_basic_user_file  /etc/nginx/passwords/localshop.htpasswd;
  }
```