Added a way for `include_timestamps` to be configured through the `ios_config` file in the Rails projects.
Added a new method on top of `association_exists?`, `polymorphic_association_exists?`, which checks the name of the association against the `as:` option of the matching associations to make sure they point to the same thing. This way, we avoid matching with associations that still point to our model, but aren't polymorphic.