HSEARCH-735 Create a test for HSEARCH-734

I've created a test case which prevents the NPE reported in HSEARCH-734 issue.
I verified that it throws the NPE with same stack trace switching hibernate search version to  3.4.0.CR2 as reported in HSEARCH-734 issue.
I added this new class in org.hibernate.search.test.embedded.update package, please I ask you to check if it is the correct choice.