Allow to split mediacenter and staticpages services
Allow to split mediacenter and staticpages services

This allows to use separate mediacenter and staticpages API endpoints by
defining the more special configuration options:

* adhocracy_service.mediacenter.rest_api_address
* adhocracy_service.mediacenter.rest_api_token
* adhocracy_service.staticpages.rest_api_address
* adhocracy_service.staticpages.rest_api_token

phihag/adhocracy,DanielNeugebauer/adhocracy,phihag/adhocracy,alkadis/vcv,liqd/adhocracy,phihag/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,phihag/adhocracy,liqd/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,alkadis/vcv,alkadis/vcv,liqd/adhocracy,phihag/adhocracy,DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,liqd/adhocracy