Add HasUuids trait when Model has id uuid primary.

[rcrosbourne]

Addresses issue #646

[jasonmccreary]

Thanks for this. While the build is passing, you need to lint the code. You may do so by running vendor/bin/pint, then submit your changes.

There are some other refactors I would make, but if you can lint your code, I'll do the rest.

[rcrosbourne]

Hey J Mac,

I ran the linter. The code now conforms to the standard.

[brocard]

thanks @rcrosbourne

[jasonmccreary]

I cleaned up a few things, but there's more I'd like to fix. The functionality and test is there. So that's good enough to merge. I'll do the rest on master before merging.