improve L5.6 support

Author: adammatysiak

composer.json

@@ -17,7 +17,7 @@
         "php": ">=5.4.0",
         "illuminate/support": "5.0.x|5.1.x|5.2.x|5.3.x|5.4.x|5.5.x|5.6.x",
         "illuminate/translation": "5.0.x|5.1.x|5.2.x|5.3.x|5.4.x|5.5.x|5.6.x",
-        "symfony/finder": "~2.3|~3.0"
+        "symfony/finder": "~2.3|~3.0|~4.0"
     },
     "autoload": {
         "psr-4": {