Object expirer does not have log_facility set explicitly
and defaults to LOG_LOCAL0, thus logging to /var/log/messages
All other swift services have been set to LOG_LOCAL2. This
patch changes object expirer to LOG_LOCAL2.
Change-Id: I037090eecc9832e7c7397a5a9e52df4a23f6c16e
Signed-off-by: Thiago da Silva <thiago@redhat.com>