Add beforeFind event to ORM\Table.

Keep things simple and add a very basic event for beforeFind. In the
future the updated behaviors will be able to use this event.

I've decided to solve a long standing problem and make it super simple
to replace the result of a find() entirely. Stopping the event and
setting a return will circumvent the entire find and return the provided
value. This makes it really easy to replace find actions with cache
results for example.