Increase Jenkins slave syslog max message size.
Increase Jenkins slave syslog max message size.

To better capture python tracebacks with syslog set the rsyslog
$MaxMessageSize to 64k. This change is being made to better accomodate
devstack-gate logging after we have stopped archiving the devstack
screen logs.

Change-Id: Ibb01f759f111d924a21c20f8521ea5db4a35e676
Reviewed-on: https://review.openstack.org/21233
Reviewed-by: Monty Taylor <37c07a49ee3d5191376d758eb1d8298b34456b8e@inaugust.com>
Reviewed-by: Jeremy Stanley <98883b97e35b7bb1ac282bb863f2e9d917db0454@yuggoth.org>
Approved: Clark Boylan <635fc31d01fa593720982fa0568e87170cedbe2c@gmail.com>
Tested-by: Jenkins

open-switch/infra_puppet-jenkins,open-switch/infra_puppet-jenkins