Ensure syslog option is honored by neutron and tempest

Syslog settings were not configured at all for these two
projects. As a result, regardless of the value of the
SYSLOG environment variable, the use_syslog options for
these two projects was always set to False.

Change-Id: Iba6155d62beffa06e5bb9ac16b06082ec64d0926
Closes-Bug: #1394024
Merge "Ensure syslog option is honored by neutron and tempest"