ISPN-4644 ISPN-4258 ISPN-4012 MassIndexer performance enhancements

https://issues.jboss.org/browse/ISPN-4644
https://issues.jboss.org/browse/ISPN-4258
https://issues.jboss.org/browse/ISPN-4012

Instead of committing on each individual document plus on each map execution, it will commit only once per MassIndexer execution.
Also avoid using the SharedWorkspace setting on all MassIndexer tests, since it does heavy synchronization assuming the index is shared (which is not)
+1
and is someone wants to introduce checkstyle gradually I won't complain ;-)
Let's just make sure we don't get dragged away with too many rules, and keep in mind that easy backporting is a priority over reformatting *existing* code.