Documents are served only when an appropriate token is included in the
query params. The token is a SHA 256 of todays date, a secret string,
and the documents ID. This way the token is only valid for one document
for one day.

The first iteration supports delivery of documents from DFØs document
service, directly to the users browser. The document is selected by a
set of query parameters, and is simply displayed inline.

This version does not include authentication or authorization.