Add archive_mode='always' option.

Heikki Linnakangas <heikki.linnakangas@iki.fi>

Commit: ffd37740ee6fcd434416ec0c5461f7040e0a11de
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: 2015-05-15T15:55:24Z
Releases: 9.5.0
Add archive_mode='always' option.

In 'always' mode, the standby independently archives all files it receives
from the primary.

Original patch by Fujii Masao, docs and review by me.

Files