Bad PATCH request (without ID) does not return HTTP 400

[maurei]

There are currently several PATCH related tests (for example Can_Patch_CamelCasedModels) that are passing but shouldn't. When according to the specs, the id attribute must be included in the request body

The PATCH request MUST include a single resource object as primary data. The resource object MUST contain type and id members.

Therefore any PATCH request without ID should return a http 400.