Allow Symfony 4

Author: dunglas

composer.json

@@ -17,15 +17,15 @@
     ],
     "require": {
         "php": ">=5.3.2",
-        "symfony/monolog-bridge": "~2.7|~3.0",
-        "symfony/dependency-injection": "~2.7|~3.0",
-        "symfony/config": "~2.7|~3.0",
-        "symfony/http-kernel": "~2.7|~3.0",
+        "symfony/monolog-bridge": "~2.7|~3.0|~4.0",
+        "symfony/dependency-injection": "~2.7|~3.0|~4.0",
+        "symfony/config": "~2.7|~3.0|~4.0",
+        "symfony/http-kernel": "~2.7|~3.0|~4.0",
         "monolog/monolog": "~1.22"
     },
     "require-dev": {
-        "symfony/yaml": "~2.3|~3.0",
-        "symfony/console": "~2.3|~3.0",
+        "symfony/yaml": "~2.3|~3.0|~4.0",
+        "symfony/console": "~2.3|~3.0|~4.0",
         "phpunit/phpunit": "^4.8"
     },
     "autoload": {