Incompatible with Laravel 5.4

[eugensuvorov]

Please, make the changes )

[leewillis77]

To add more detail to this, amending the composer.json for a Laravel 5.3 project to Laravel 5.4, e.g.

"laravel/framework": "5.4.*",

results in the following error when running composer install:

    - anhskohbo/no-captcha 2.2.0 requires illuminate/support 5.0.*|5.1.*|5.2.*|5.3.* -> satisfiable by laravel/framework[v5.3.29], illuminate/support[v5.0.0, v5.0.22, v5.0.25, v5.0.26, v5.0.28, v5.0.33, v5.0.4, v5.1.1, v5.1.13, v5.1.16, v5.1.2, v5.1.20, v5.1.22, v5.1.25, v5.1.28, v5.1.30, v5.1.31, v5.1.41, v5.1.6, v5.1.8, v5.2.0, v5.2.19, v5.2.21, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.31, v5.2.32, v5.2.37, v5.2.43, v5.2.45, v5.2.6, v5.2.7, v5.3.0, v5.3.16, v5.3.23, v5.3.4].

Are there known issues with Laravel 5.4, the PR in #60 suggests not?

[anhskohbo]

Fixed #60