Add laravel auth provider to check already authenticated users and tests

[gabrielkoerich]

I'm using dingo api in an AngularJS app, so I won't authenticate users every request.

This auth provider is just to check if the user is already logged in, if not it will throw UnauthorizedHttpException.

Ps: Not sure what name to use, so I just called it "Laravel Provider"

[jasonlewis]

I'm not terribly keen on this as an API should be stateless. It shouldn't work like this. You should be using basic authentication or, even better, use access tokens (OAuth 2.0).