Moved zf-configuration controllers into admin

- Allows zf-configuration to have zero dependencies, other than on ZF2.
- All other admin API controllers are in this module as well; should keep them
  together.
Merge branch 'feature/configuration-controllers'

Moves controllers from zf-configuration into this module, which means:

- fewer dependencies in zf-configuration (and removes a circular dep)
- all admin api controllers are now under the same umbrella