phpunit and behat should be placed in composer require-dev not require

That is because if you use this library in production you end up with autoloading whole phpunit and behat, of course we don't want to do that

See http://getcomposer.org/doc/04-schema.md#require-dev for more info
Merge pull request #14 from konradpodgorski/feature/composer-require-dev

phpunit and behat should be placed in composer require-dev not require