Issue #19. Mvn site repository configuration

This change introduces a method to manage snapshot builds for the public and for samplestack.  It works great!

I made a wiki page about what this does

https://github.com/marklogic/java-client-api/wiki/Using-snapshot-builds

It works for samplestack just fine, so I'm happy with the results for EA-2.  I do want everyone to understand what's going on.