Add the Symfony PHPUnit bridge to catch deprecations

Author: stof

composer.json

@@ -25,6 +25,10 @@
         "instaclick/php-webdriver":  "~1.1"
     },
 
+    "require-dev": {
+        "symfony/phpunit-bridge": "~2.7"
+    },
+
     "autoload": {
         "psr-4": {
             "Behat\\Mink\\Driver\\": "src/"