synchronizing transaction r/w per http://akiban.github.io/persistit/javadoc/com/persistit/Transaction.html#_threadManagement
updating pom to use persist it 3.3
creating tree on kv store instantiation instead of on first use. This was causing problems because a tree would be instantiated within one tx, then another tx would try to access it before the other tx was committed.
putting transaction around tree creation
moving transaction start to after test kv store was created in kv store tests
un-hacking SessionId creation