merged branch cordoval/patch-2 (PR #787)

This PR was submitted for the master branch but it was merged into the 1.0 branch instead (closes #787).

Discussion
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fix docblock

Commits
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fbf12a5 fix docblock

src/Silex/Application.php

@@ -470,7 +470,7 @@ class Application extends \Pimple implements HttpKernelInterface, TerminableInte
     /**
      * Handles the request and delivers the response.
      *
-     * @param Request $request Request to process
+     * @param Request|null $request Request to process
      */
     public function run(Request $request = null)
     {