Merge branch 'improve-session-expiry' into 'master'

Fix "remember me" sign in option

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4006

Prior to this change, 'remember me' was effectively always on because
the `_gitlab_session` cookie was always made persistent. With this
change it becomes possible again to have `_gitlab_session`be a session
cookie when 'remember me' is unchecked.

See merge request !4004

config/initializers/session_store.rb

@@ -22,7 +22,7 @@
     key: '_gitlab_session',
     secure: Gitlab.config.gitlab.https,
     httponly: true,
-    expire_after: Settings.gitlab['session_expire_delay'] * 60,
+    expires_in: Settings.gitlab['session_expire_delay'] * 60,
     path: (Rails.application.config.relative_url_root.nil?) ? '/' : Gitlab::Application.config.relative_url_root
   )
 end