use blob schemas where possible in API validation

[bhearsum]

We've got jsonschemas that can validate all of the different types of Release blobs. It would be great if we could use those as part of the swagger specs, because it would allow us to generate clients that could do client-side blob validation, which can make clients much friendlier.

Swagger only supports a subset of jsonschema, so it may not be possible for all of the current blob types.

(Imported from https://bugzilla.mozilla.org/show_bug.cgi?id=1381514)