add directoryFactory to example, w/ default to FS
add directoryFactory to example, w/ default to FS

git-svn-id: 6c059844b382e4b70377f6a3151bbb76419eaccf@925431 13f79535-47bb-0310-9956-ffa450edef68

cscorley/solr-only-mirror,cscorley/solr-only-mirror,cscorley/solr-only-mirror