Except socket.error if syslog isn't running

When setting `use_syslog=true` and restarting the service, if syslog (or
rsyslog) isn't running, except the error and inform the user instead
of failing with a generic Errno 111.

Change-Id: Ie4ce3e84dcff838b569d6e2711aee5ea21c01083
Partial-Bug: 1328501
Merge "Except socket.error if syslog isn't running"