snapshot builds

[Jim Donofrio]

I reconfigured Jenkins to deploy snapshots for the sources, javadoc and 
hadoop1 and 2 jars. This will help Jacon Metcalf test the problem with 
Avro he was having and allow other users to test fixes we add in without 
having to build from source themselves.

Jenkins will run:
mvn clean package
mvn clean deploy -Dhadoop.version=2
mvn clean deploy
This is so that no artifacts are deployed unless both build correctly.