Do not generate foreign key for simple UUID column

[jasonmccreary]

This PR fixes an issue reported where uuid columns generated a foreign key relationships. In the process of solving this, I also added a feature where uuid columns with a conventional name automatically creates the relationship.

For example:

models:
  Subscription:
    product_id: uuid

Creates a belongsTo relationship for Product.

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Closes #417

[jasonmccreary]

@tanthammar, can you pull this branch (dev-fix-417) and see if it works as expected.

[tanthammar]

Thank you!
Yes it works :)