merged branch drock/exception-wrapper-use-HttpExceptionInterface (PR #530)

This PR was merged into the master branch.

Commits
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72506950 Added use statement for HttpExceptionInterface

Discussion
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Added use statement for HttpExceptionInterface

The Exception Wrapper recent refactoring added a reference to HttpExceptionInterface but not a use statement for it.  This can cause the instance of check in there to fail causing you to always get a 500 error code.

src/Silex/ExceptionListenerWrapper.php

@@ -12,6 +12,7 @@
 namespace Silex;
 
 use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
 use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
 use Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent;