adding symfony 4.0 support

Author: zaherg

composer.json

@@ -17,9 +17,9 @@
     "require": {
         "ext-zip": "*",
         "guzzlehttp/guzzle": "~4.0|~5.0|~6.0",
-        "symfony/console": "~2.3|~3.0",
-        "symfony/filesystem": "~2.3|~3.0",
-        "symfony/process": "~2.3|~3.0"
+        "symfony/console": "~2.3|~3.0|~4.0",
+        "symfony/filesystem": "~2.3|~3.0|~4.0",
+        "symfony/process": "~2.3|~3.0|~4.0"
     },
     "bin": [
         "botman"