Show Download only for Authorized Users

[srappel]

Currently, restricted data will not show the download button. However, our SSO layer is on the web server so this hides the download URL even from UWM users.

As a temporary fix, I simply set all datasets to be public in #85

But we need to think about doing something better.

[srappel]

This might be more of a problem as we harvest restricted datasets from Stanford, Princeton, etc.

The only thing indicating their restriction is that tiny lock icon near the title. We might want to consider display notes for this.