Bug 13876: Fallback to /tmp if logdir is not writable

Bug 13876: Fallback to /tmp if logdir is not writable

If the logdir directory is not writable by the koha user, the installer
should not explode.
This patch uses a temporary directory as a fallback.
That means that the history won't be kept.

Test plan:
0/ Generate an update (modify updatedatabase.pl and kohaversion)
1/ Make sure the permission are not correct on $logdir
2/ Go on the interface and execute the update entry.
3/ Confirm that the log has been created in a temporaty directory.

Retry with correct permissions and confirm the log will be created in
$logdir.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Adding a follow-up for completely resolving encountered issues.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Chris Nighswonger <cnighswonger@foundations.edu>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>