- added setter for realObjectId to ObjectId since old approach of bson to js host obj creation through constructor was not working consistently in repeated test executions
added more global functions and bulk insert handling

- bulk insert handling now implemented
- added _srand and _rand global js functions
DISCOVERY: several tests, particularly around capped collections, rely on test commands that are enabled by running the mongo daemon as follows: mongod --setParameter enableTestCommands=1