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
diff --git a/lib/tempest b/lib/tempest
index 8931300..d3fb9fb 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -247,6 +247,7 @@
         fi
     fi
 
+    iniset $TEMPEST_CONF DEFAULT use_syslog $SYSLOG
     # Oslo
     iniset $TEMPEST_CONFIG DEFAULT lock_path $TEMPEST_STATE_PATH
     mkdir -p $TEMPEST_STATE_PATH