Finalize OSM demo

This commit will finish the OSM demo
Update PA MapReduce code to work on UT cluster

This commit updates the PreAggregate MapReduce README to include some
additional info on compiling the JAR and adds an extra parameter to
specify the IP address of the Yarn ResourceManager, which is needed to
run it on the UT Yarn cluster (and likely other clusters as well)
Fix a bug with the GeoSrvr ext and keyword support

Keyword support no longer worked in the GeoServer PA extension due to a
small bug into checking the type of NominalAxis. Fixed by properly
checking for a wordlist-based NominalAxis.