BDD: Update structure to for the inheritance fix

This belongs to a inheritance fix that involve:
- [ ] ezsystems/BehatBundle (PR coming)
- [x] ezsystems/ezpublish-community (PR coming)
- [x] ezsystems/ezpublish-kernel#872 (EzPublishLegacyBundle and EzPublishRestBundle) (PR coming)
- [x] ezsystems/DemoBundle#90

Todo:
- [x] change classes namespaces to reflect changes
- [x] remove unneeded paths

**Needs to pass on travis**:
- [ ]  - (PR coming)