Issue #2498515 by Berdir, neclimdul: Update additional Symfony Components to 2.7.0

.gitattributes

core/composer.lock

core/vendor/composer/autoload_namespaces.php

core/vendor/composer/autoload_psr4.php

core/vendor/composer/installed.json

core/vendor/symfony/browser-kit/.gitignore

core/vendor/symfony/browser-kit/CHANGELOG.md

core/vendor/symfony/browser-kit/Client.php

core/vendor/symfony/browser-kit/Cookie.php

core/vendor/symfony/browser-kit/CookieJar.php

core/vendor/symfony/browser-kit/History.php

core/vendor/symfony/browser-kit/LICENSE

core/vendor/symfony/browser-kit/README.md

core/vendor/symfony/browser-kit/Request.php

core/vendor/symfony/browser-kit/Response.php

core/vendor/symfony/browser-kit/Tests/ClientTest.php

core/vendor/symfony/browser-kit/Tests/CookieJarTest.php

core/vendor/symfony/browser-kit/Tests/CookieTest.php

core/vendor/symfony/browser-kit/Tests/HistoryTest.php

core/vendor/symfony/browser-kit/Tests/RequestTest.php