investigate - headers check with extensions

[mickeyn]

I see the examples in the extensions sections sending headers that should produce errors according to the spec.

see: http://jsonapi.org/format/#content-negotiation-servers
vs. http://jsonapi.org/extensions/bulk/#creating-multiple-resources

need to investigate this / open an issue with {json:api}

[mickeyn]

http://discuss.jsonapi.org/t/clarification-on-extensions-media-type-headers/296/1

[mickeyn]

this is related to extensions support - not relevant for the CPAN release

[mickeyn]

as advised by the {json:api} elders, we should wait with the extensions as they are about to change the whole thing in the spec.
on my branch (https://github.com/mickeyn/PONAPI/tree/mickey/bulk_extension) you can find temp. implementation working with the current rules (except for the actual implementation in the repository)