Make the Taste Demo more automated.

Would be really cool if the Taste Demo (http://lucene.apache.org/mahout/taste.html#demo) was easier to get up and going. For instance, we could have an Ant task that automatically gets the data and puts it into the work directory just like we do for Reuters, Wikipedia and Twenty News. Then, we could also ship Jetty w/ the examples, such that one just needs to do

java -jar start.jar

to fire up the WAR and have it running (Solr does this)