Ernst en arjen maken een dashboard

TODO's

Ernst:
- [ ] Create StateService.
- [ ] Migrate state to state service.
- [ ] Add type to layer and rename old type to format (FE and BE) [asset, raster, event]
- [ ] Adapt getData to incorporate type and format in options

Arjen:
- [ ] Create dashboard directive.
- [ ] Create dashboard template.
- [x] Update URL service and url-controller
- [x] Update index.html according to scope.context

Bonus:
- [ ] Functionality to color bars.
- [ ] Hover or click functionality on bars.