Allow Symfony 4

Author: VolCh

composer.json

@@ -10,7 +10,7 @@
     ],
     "require": {
         "php": ">=5.3.2",
-        "symfony/console": "~2.3 || ~3.0"
+        "symfony/console": "~2.3 || ~3.0 || ~4.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.8.36 || ~5.7 || ~6.4"