Configuration validator

[fabiodomingues]

Create a configuration validator to support users when they are configuring and there is a typo or something that is not expected.

This is an example of the supported configuration for now:

{:layers {:controller {:defined-by         ".*\\.controller\\..*"
                       :accessed-by-layers #{}}
          :logic      {:defined-by         ".*\\.logic\\..*"
                       :accessed-by-layers #{:controller}}
          :model      {:defined-by         ".*\\.model\\..*"
                       :accessed-by-layers #{:logic :controller}}}}