journal: Persist journal files

Journald flushes jorunal entries to disk (by default) if
/var/log/journal exists. Previously this path did not exists.
Now this path is created on boot and the SELinux permissions are
restored.

rhbz#917523

Change-Id: If6ac14e520437785c8fa1174d5ede25e65226f80
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>