delete the utility controller

Motivation:

At the moment the utility controller is for obtaining
access and refresh token. These are no longer needed
at this time. Since the helmholtz-marketplace-webapp
will is now a dependency of this project, there is no
need for the index.html page.

Modification:

- delete the controller and index.html page

Result:

The server now render the helmholtz-marketplace-webapp
static files.

Target: master
4 jobs for master in 8 minutes and 13 seconds (queued for 1 second)