Laravel 5.3 compatibility added

[mspiderv]

I tested this with Laravel 5.3.21.

[aethr]

I tested this via a patch file on some basic functionality in a Laravel v5.3.19 project and didn't have any issues.

[Stubbs]

The unit tests for this are failing because of the differences between Laravel 5.2 & 5.3, have a look at the changes on my latest comment to see what I had to fix:

https://github.com/Stubbs/laravel5-jsonapi/commit/5af2634e1345beae257c644c5cdef1345db095f7

[dneckel]

Stubbs@5af2634 is working good for me 👍