Merge branch '3.4' into 4.0

* 3.4:
  "replace" 7.0 & 5.6 polyfills

Author: fabpot

composer.json

@@ -5,6 +5,7 @@
     "description": "Project description",
     "require": {
         "php": "^7.1.3",
+        "ext-iconv": "*",
         "symfony/console": "^4.0",
         "symfony/flex": "^1.0",
         "symfony/framework-bundle": "^4.0",
@@ -30,6 +31,11 @@
             "App\\Tests\\": "tests/"
         }
     },
+    "replace": {
+        "symfony/polyfill-apcu": "*",
+        "symfony/polyfill-php70": "*",
+        "symfony/polyfill-php56": "*"
+    },
     "scripts": {
         "auto-scripts": [
         ],