Merge branch '2.8' into 3.0

* 2.8: (25 commits)
  [Console] Fix an autocompletion question helper issue with non-sequentially indexed choices
  [Process] Fix pipes handling
  Mentioned the deprecation of deep parameters in UPGRADE files
  [Filesystem] Fix false positive in ->remove()
  [Filesystem] Cleanup/sync with 2.3
  [Validator] Fix the locale validator so it treats a locale alias as a valid locale
  [HttpFoundation] Fix transient test
  [HttpFoundation] Add a dependency on the mbstring polyfill
  [2.7] update readme files for new components
  add readme files where missing
  [2.8] update readme files for new components
  fix lowest TwigBridge deps versions
  reference form type by name on Symfony 2.7
  [EventDispatcher] fix syntax error
  Don't use reflections when possible
  Don't use reflections when possible
  [Form] Update form tests after the ICU data update
  [Intl] Update tests and the number formatter to match behaviour of the intl extension
  [Intl] Update the ICU data to version 55
  [Intl] Fix the update-data.php script in preparation for ICU 5.5
  ...

Conflicts:
	UPGRADE-2.8.md
	UPGRADE-3.0.md
	src/Symfony/Bridge/Twig/composer.json
	src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/FragmentRendererPass.php
	src/Symfony/Component/Console/Helper/DialogHelper.php
	src/Symfony/Component/Console/Helper/ProgressHelper.php
	src/Symfony/Component/Console/Tests/Helper/LegacyDialogHelperTest.php
	src/Symfony/Component/HttpFoundation/composer.json
	src/Symfony/Component/Security/Core/README.md
	src/Symfony/Component/Security/Csrf/README.md
	src/Symfony/Component/Security/Http/README.md
	src/Symfony/Component/Validator/Constraints/LocaleValidator.php

Author: nicolas-grekas

DependencyInjection/Compiler/LoggingTranslatorPass.php

@@ -36,8 +36,7 @@ public function process(ContainerBuilder $container)
             $definition = $container->getDefinition((string) $translatorAlias);
             $class = $container->getParameterBag()->resolveValue($definition->getClass());
 
-            $refClass = new \ReflectionClass($class);
-            if ($refClass->implementsInterface('Symfony\Component\Translation\TranslatorInterface') && $refClass->implementsInterface('Symfony\Component\Translation\TranslatorBagInterface')) {
+            if (is_subclass_of($class, 'Symfony\Component\Translation\TranslatorInterface') && is_subclass_of($class, 'Symfony\Component\Translation\TranslatorBagInterface')) {
                 $container->getDefinition('translator.logging')->setDecoratedService('translator');
                 $container->getDefinition('translation.warmer')->replaceArgument(0, new Reference('translator.logging.inner'));
             }

README.md

@@ -0,0 +1,10 @@
+FrameworkBundle
+===============
+
+Resources
+---------
+
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)