Add before_validation,after_validation options to hook into the validation process

[ahx]

This adds before_validation, after_validation options to modify data before or after validation. The insert_property_defaults now is one of these before hooks.
One use case of this is to parse data based on your JSON Schema before or after the validation is run.

The after_validation option should basically solve #49.

In it's current state this only works when validating objects. 😬 What do you think?

[ahx]

Should we name these before_object_validation / after_object_validation to make clear that this is only useful when validating a Hash? 🤔

[davishmcclurg]

This is cool! It's great to see it used to implement insert_property_defaults.

Should we name these before_object_validation / after_object_validation to make clear that this is only useful when validating a Hash? 🤔

What do you think about before_property_validation/after_property_validation? That is consistent with insert_property_defaults.

[ahx]

I was trying to implement handling readOnly via a before-hook, but I think we should pass the parent schema to these Procs as well to be useful for a use-case like that. I'll push another commit for that tomorrow.

[ahx]

I have changed the hook signature so that the parent schema is passed as well.

proc { |data, property, property_schema, schema| … }

[davishmcclurg]

Thanks @ahx!

[davishmcclurg]

Released in 0.2.16

[ahx]

@davishmcclurg That it so cool.
I think I can push this to cover most of my use cases for #55 or #49 in my projects. 🚀
Thanks for working on this with me. ❤️