Serve files from the symlink not the release dir
Serve files from the symlink not the release dir

Using `Rails.root` as the path to serve the files from means that Rails
will tell nginx to serve something like
`/data/vhost/publisher.preview.alphagov.co.uk/releases/20150706083530/re
ports/organisation_content.csv`, which is incorrect.

alphagov/publisher,alphagov/publisher,leftees/publisher,leftees/publisher,telekomatrix/publisher,telekomatrix/publisher,telekomatrix/publisher,leftees/publisher,telekomatrix/publisher,alphagov/publisher,leftees/publisher