Closes #313 - Hibernate validator missing from Twill classpath

With this pull request, Fluo-20 branch should now run in YARN.  However, there may be a better way to fix this issue long-term.
We should probably externalize this and push it into a startup script or external file.  This list seems very dependency specific and it would be nice if users could change it as deps change.  Or were you thinking of this as a short term fix until something is done for #314?