cleanup, whitespace, STS warnings
cleanup, updated to latest release plugin
Merge pull request #90 from tomwidmer/collection-unset-bug

Make AbstractSession.getCachedInstance meet contract of method.
Merge pull request #91 from tomwidmer/embedded-coll-dbrefs

MongoDB: ensure that to-manys inside embedded entities use reference map...
MongoDB optimistic locking updates implemented.

Version is now atomically updated using a 'compare and exchange' type
atomic operation, avoiding possible race conditions in a
multi-threaded or multi-process situation.

Note that this means at least an 'acknowledge' level of write concern is always
used for versioned entities.

Added a corresponding note to the docs.