List data sets

This now works on preview if the jenkins job is set to run the branch. For it to work in other environments, the user must be given access to the app in signon and to the dataset 'test' in the stagecraft of that environment.

One question though - should we aim for more descriptive html as the css selector in Rob's commit requires, or is the fixed selector okay (it doesn't require changes to the admin app but maybe the admin app html should be more descriptive?)