Laravel 5.6 commands must be called from handle method.

[patronelli87]

Fixes this:

php artisan make:migration:json

   ReflectionException  : Method Mojopollo\Schema\Commands\MakeMigrationJsonCommand::handle() does not exist

  at /var/www/testing.xppia.com/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php:135
    131|             $callback = explode('::', $callback);
    132|         }
    133|
    134|         return is_array($callback)
  > 135|                         ? new ReflectionMethod($callback[0], $callback[1])
    136|                         : new ReflectionFunction($callback);
    137|     }
    138|
    139|     /**

  Exception trace:

  1   ReflectionMethod::__construct(Object(Mojopollo\Schema\Commands\MakeMigrationJsonCommand), "handle")
      /var/www/testing.xppia.com/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php:135

  2   Illuminate\Container\BoundMethod::getCallReflector()
      /var/www/testing.xppia.com/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php:115

  Please use the argument -v to see more details.

[coveralls]

Coverage remained the same at 100.0% when pulling ea1c4c8 on rafflesargentina:master into cf8f50c on mojopollo:master.