Added an example script for moving files to HDFS

This script moves files to HDFS. Nfcapd should call this script after
each cycle (option -x).

Source config example:
'peer1' => { 'port' => '9996', 'col' => '#0000FF', 'optarg' => '-x "/opt/nfsen/bin/nf2hdfs %d/%f"' }

If you have more than a few sources and notice occasional drops in graphs,
consider increasing PROFILERDELAY.