Does not work with symfony/finder lower than 2.2 version
Does not work with symfony/finder lower than 2.2 version

```
1) SwaggerMiddlewareTest\GeneratorTest::testCanGenerate
LogicException: You must call the in() method before iterating over a Finder.

/home/svycka/Documents/projects/github/swagger-middleware/vendor/symfony/finder/Symfony/Component/Finder/Finder.php:518
/home/svycka/Documents/projects/github/swagger-middleware/vendor/zircote/swagger-php/src/functions.php:39
```

zircote/swagger-php,DerManoMann/swagger-php