Major refactoring of the MongoDB queries to make the code simpler and lock operations significantly more efficient
Added test for one read lock holder extending its lock while another read lock holder already has a much later expiring lock. This this case the new extender should not impact the lock document expire time.
history and read me updates for release
Fixed issue with use of $currentDate on MongoDB 2.4.x
Merge branch 'mongodb_2.4'
Bump versions for release and update history