Set variables in rsyslog.conf to disable rate-limiting.

Per Bug https://bugs.launchpad.net/openstack-ci/+bug/1024487, this will
modify the rate-limiting setting for rsyslog.conf.  If rate-limiting is
being used the addition will set it to 0 otherwise the addition will
add the variables to the configuration file and set them to 0.

Implements: Variables "$SystemLogRateLimitBurst 0", and
"$SystemLogRateLimitInterval 0" in "/etc/rsyslog.conf". These changes
are persuent to what has been outlined in the rsyslog docs as found
here : http://www.rsyslog.com/tag/SystemLogRateLimitInterval/

Updated commit implements changes in code and placement post code
review. Recent change implements the "SystemLogRateLimitBurst" in first
if statement, which was "SystemLogRateLimitInterval" and wrong.

Fixes: Bug 1024487
Change-Id: I2637889cbe9e5e87bbfc0f1bb5047abae34d953c

stack.sh

@@ -754,6 +754,22 @@ EOF
 EOF
         sudo mv /tmp/90-stack-s.conf /etc/rsyslog.d
     fi
+
+    RSYSLOGCONF="/etc/rsyslog.conf"
+    if [ -f $RSYSLOGCONF ]; then
+        sudo cp -b $RSYSLOGCONF $RSYSLOGCONF.bak
+        if [[ $(grep '$SystemLogRateLimitBurst' $RSYSLOGCONF)  ]]; then
+            sudo sed -i 's/$SystemLogRateLimitBurst\ .*/$SystemLogRateLimitBurst\ 0/' $RSYSLOGCONF
+        else
+            sudo sed -i '$ i $SystemLogRateLimitBurst\ 0' $RSYSLOGCONF
+        fi
+        if [[ $(grep '$SystemLogRateLimitInterval' $RSYSLOGCONF)  ]]; then
+            sudo sed -i 's/$SystemLogRateLimitInterval\ .*/$SystemLogRateLimitInterval\ 0/' $RSYSLOGCONF
+        else
+            sudo sed -i '$ i $SystemLogRateLimitInterval\ 0' $RSYSLOGCONF
+        fi
+    fi
+
     echo_summary "Starting rsyslog"
     restart_service rsyslog
 fi