ISPN-263 Handle cluster partitions

https://issues.jboss.org/browse/ISPN-263

I added one more commit with some test fixes.
any logger in Hibernate Search looks like this:

    private static final Log log = LoggerFactory.make();

See the factory:
https://github.com/hibernate/hibernate-search/blob/master/engine/src/main/java/org/hibernate/search/util/logging/impl/LoggerFactory.java#L22-L26