Use Codeception 2.3 development branch

Author: janhenkgerritsen

composer.json

@@ -12,7 +12,7 @@
   "require-dev": {
     "phpunit/phpunit": "~4.0",
     "phpspec/phpspec": "~2.1",
-    "codeception/codeception": "2.2.x-dev",
+    "codeception/codeception": "2.3.x-dev",
     "symfony/dom-crawler": "~3.0",
     "symfony/css-selector": "~3.0"
   },