Merge branch '2.8'

* 2.8:
  Remove whitespaces between <input> and <label>
  [Translation][File dumper] allow new child classes to implement only formatCatalogue.
  [travis] Remove PHP 7 from allowed failures
  [Translation] Clean whitespaces and EOL in xliff-core-2.0.xsd
  [Finder] Optimize the hot-path
  Update Process.php

Conflicts:
	.travis.yml
	composer.json
	src/Symfony/Bridge/Doctrine/composer.json

Author: nicolas-grekas

Dumper/FileDumper.php

@@ -114,7 +114,10 @@ protected function formatCatalogue(MessageCatalogue $messages, $domain, array $o
      *
      * @deprecated since version 2.8, to be removed in 3.0. Overwrite formatCatalogue() instead.
      */
-    abstract protected function format(MessageCatalogue $messages, $domain);
+    protected function format(MessageCatalogue $messages, $domain)
+    {
+        throw new \LogicException('The "FileDumper::format" method needs to be overwritten, you should implement either "format" or "formatCatalogue".');
+    }
 
     /**
      * Gets the file extension of the dumper.