change frontpage of BD4NRG environment

Currently, https://bd4nrg.semantic-treehouse.nl brings the users immediately to the vocabularies page.

In order for users (research project partners) to understand where they've arrived, we need to change the frontpage to something like that of the ZeroW enviroment, see https://zerow.semantic-treehouse.nl.

I've made a design:

The source of this design is a powerpoint slide in T4SMM - Team\Work\Projecten\BD4NRG