add support for Laravel 5.5

[claytonrcarter]

This also allows the package to be auto-discovered. Tests are passing and I have tried it out (successfully!) in a 5.5.13 project. Thanks!

[coveralls]

Coverage remained the same at 100.0% when pulling 45a5e69 on claytonrcarter:laravel-55 into 360c08d on neoxia:master.

[thomasruiz]

We need to tag to 1.2 after the merge @alexandre-butynski.

[alexandre-butynski]

Thanks for that @claytonrcarter ! I have just released v1.1.1.

@thomasruiz, I have chosen to stay on the 1.1.* version because there is no breaking change.