Automated validation of search/filter fields

[pond]

Sort of related to #255 - Hoodoo framework search/filter additions automatically validate the header quantities, so things like a created_by search is rejected with a reasonably informative 422 response should the search field's value not be a valid UUID.

Currently, there's no way for a resource interface class to request something similar. Models can provide quite complex mappings to get from search/filter request down to SQL level, while interfaces can give a basic list of things that are searchable or filterable, but there's no easy place to have validation and error returns done other than hand-coding it at Some Appropriate Point in the implementation flow.

This could be improved upon dramatically.