Logserver: Use RainerScript for log rules.

Use RainerScript ``if'' statements and ``action()'' directives for
saving of client logs instead of the traditional facility.severity
selectors.  There are a couple of reasons for this:

 - We can use program name, not just syslog facility, to select
   which messages should go to the audit logs.  Non-audit local6
   messages will not be misplaced.
 - We can use the more readable ``stop'' directive instead of the
   tilde ("~").
 - We want to be able to provide more parameters to at least some
   actions than the traditional selector rules can do, unless you
   use deprecated $ directives.  (This will be done in a later
   commit.)

The rules for local logs (the ones coming from the log server itself
and stored in /var/log) are left as traditional selectors, because
A) they are simple rules, and easier to read that way, and B) that's
the way they are written in the standard RHEL-7 /etc/rsyslog.conf
file where we copied them from.

templates/rsyslog-el7.conf-logserver.erb

@@ -206,16 +206,26 @@ module(load="builtin:omfile"
 # All logs, remote as well as local
 
 
-# auditing of login nodes
-local6.*			-?AuditLogfile;NSCLogFormatSourcePri
-local6.*			~
+# Audit logs of cluster login nodes
+if $syslogfacility-text == "local6" and $programname == "audispd" then
+{
+    action(type="omfile"  dynaFile="AuditLogfile"
+	   template="NSCLogFormatSourcePri")
+    # These are extremely voluminous, so don't let them be processed
+    # (and thus stored) by later rules.
+    stop
+}
 
-*.*				?LogFile;NSCLogFormat
+# Everything else stored in the normal /syslogs/... paths
+action(type="omfile"  dynaFile="LogFile")
 
-# We log everything to one file as well, for easy 'tail -f':ing
-# This file is logrotated every day, with only one generation
-# saved.
-authpriv.*			-/syslogs/logstream;NSCLogFormatSourcePri
+# We log authpriv information to one file as well, for easy 'tail -f':ing
+# This file is logrotated every day, with only one generation saved.
+if $syslogfacility-text == "authpriv" then
+{
+    action(type="omfile"  file="/syslogs/logstream"
+	   template="NSCLogFormatSourcePri")
+}