Merge pull request #639 from tinwelint/index-recovery-issue

Exposes and fixes lucene recovery issue
Updated changelogs for 2.0
Fix for broken test
Safe-guard closing of IndexReaders used in the global read-only StatementContext.

- Added CleanupService utility for cleaning up unmanaged resources when
  the GC collects them, if not cleaned up manually earlier.

co-author: Tobias Lindaaker