Merge branch '2.8' into 3.0

* 2.8:
  [#6032] some tweaks for the autowiring feature
  [DependencyInjection] Autowiring doc
  [Security] Include guard firewall configuration sample.
  Added doc about Homestead's Symfony integration
  [2.8] Add "How to Use Multiple Guard Authenticators" cookbook documentation
  remove note about memory spool handling on CLI
  [Cookbook][Serializer] fix wording
  Document translation_domain setting for choice fields
  translation_domain doc fix
  choice_translation_domain doc fix
  Travis fix
  Update entity.rst

Conflicts:
	cookbook/console/request_context.rst
	cookbook/serializer.rst

Author: xabbuh

book/routing.rst

@@ -1582,7 +1582,7 @@ URL) rather than the ``path()`` function (which generates a relative URL):
     The host that's used when generating an absolute URL is automatically
     detected using the current ``Request`` object. When generating absolute
     URLs from outside the web context (for instance in a console command) this
-    doesn't work. See :doc:`/cookbook/console/sending_emails` to learn how to
+    doesn't work. See :doc:`/cookbook/console/request_context` to learn how to
     solve this problem.
 
 Summary