Use rpm -q rsyslog rather rpm -qa rsyslog

Comparing the time for rpm -qa vs rpm -q

```
$ time rpm -qa --qf "%{VERSION}" "rsyslog"
7.4.7
real    0m1.638s
user    0m1.498s
sys     0m0.132s
```

vs

```
$ time rpm -q --qf "%{VERSION}" "rsyslog"
7.4.7
real    0m0.033s
user    0m0.026s
sys     0m0.005s
```

So that saves 1 second per puppet run.

lib/facter/rsyslog_version.rb

@@ -19,7 +19,7 @@
         Facter::Util::Resolution.exec("rsyslogd -v | head -n 1 | awk '{print $2}' | sed 's/,//g'")
       else
         # Fall back to rpm to determine version
-        command = 'rpm -qa --qf "%{VERSION}" "rsyslog"'
+        command = 'rpm -q --qf "%{VERSION}" "rsyslog"'
         version = Facter::Util::Resolution.exec(command)
         Regexp.last_match(1) if version =~ %r{^(.+)$}
       end