Merge branch 'prepare_release_2.3.4' into 'master'

composer.json

doc/changelog.rst

phpunit.xml.dist

src/Silex/Application.php

src/Silex/EventListener/LogListener.php

src/Silex/ExceptionHandler.php

src/Silex/ExceptionListenerWrapper.php

src/Silex/Provider/Session/AbstractSessionListener.php

src/Silex/Provider/Session/AbstractTestSessionListener.php

src/Silex/Provider/Session/SessionListener.php

src/Silex/Provider/Session/TestSessionListener.php

src/Silex/WebTestCase.php

tests/Silex/Tests/Application/SecurityTraitTest.php

tests/Silex/Tests/ApplicationTest.php

tests/Silex/Tests/CallbackResolverTest.php

tests/Silex/Tests/ControllerCollectionTest.php

tests/Silex/Tests/ControllerTest.php

tests/Silex/Tests/ExceptionHandlerTest.php

tests/Silex/Tests/LazyRequestMatcherTest.php

tests/Silex/Tests/Provider/FormServiceProviderTest.php