Rewrite WebQR API:
  - User name and graph are the same.
  - User name is not send in JSON/data but is taken from the HTTP cookies header (TODO).
  - The Web browser now assigns the local URI (Prolog still assigns the global URI).
  - The local URI is not send in JSON/data when it is the request URI.
  - The user DB of PCG is used to retrieve the model language and the prefered natural languages.
Merge branch 'master' of https://github.com/wouterbeek/WebQR