merged branch drak/flashinterface (PR #3719)

Commits
-------

cde1c52 [HttpFoundation] Add missing method in flash interface.

Discussion
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[HttpFoundation] Add missing method in flash interface.

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: #3711
Todo: -

src/Symfony/Component/HttpFoundation/Session/Flash/FlashBagInterface.php

@@ -20,6 +20,14 @@ use Symfony\Component\HttpFoundation\Session\SessionBagInterface;
  */
 interface FlashBagInterface extends SessionBagInterface
 {
+    /**
+     * Adds a flash message for type.
+     *
+     * @param string $type
+     * @param string $message
+     */
+    public function add($type, $message);
+
     /**
      * Registers a message for a given type.
      *