Revert 'factory_girl-rails seems to load definitions properly now'

I thought this was working now, but it turns out it only works if rspectacular
is loaded as part of a Rails app. If it's loaded as part of an Engine, the
factory definitions need to be explicitly loaded.

This reverts commit 8c8bfe839178da950328cc2efddb5661d2b9e14f.
Feature: Add StrongParameters configuration defaults for specs