Add paths for Splunk forwarder to incl list

The Splunk Universal Forwarder follows the same directory structure as the main Splunk package, but it is rooted in /opt/splunkforwarder instead of /opt/splunk.

Managing forwarder configuration with Puppet via Augeas is actually more important to me, since there will be a good deal more variation in forwarders and a good many more of them. (I don't use the Splunk deployment server for various reasons.)

Thanks!