Merge branch '2.8' into 3.1

* 2.8:
  blocked monolog bundle to avoid a deprecation notice
  updated VENDORS for 2.7.21

Author: fabpot

composer.json

@@ -17,7 +17,7 @@
         "doctrine/doctrine-bundle": "^1.6",
         "doctrine/doctrine-cache-bundle": "^1.2",
         "symfony/swiftmailer-bundle": "^2.3",
-        "symfony/monolog-bundle": "^2.8",
+        "symfony/monolog-bundle": "~2.11.3",
         "symfony/polyfill-apcu": "^1.0",
         "sensio/distribution-bundle": "^5.0",
         "sensio/framework-extra-bundle": "^3.0.2",