Moved the utility Mongo class to it's own source code file, MongoDb.cs.
Added new TransactionManager class to MongoDb PokerDemo application, outlining the functionality we'll need to provide MongoDb atomicy.
Added stub for new method UpdateAsDone in the TransactionManager, to be used to take a transaction from "committed" to "done".
Extended MongoDb domain model with a few properties on the AccountBalanceTransaction class, making it simple to check the state of a transaction.
Implemented TransactionManager.UpdateAsDone.
Implemented a new version of the MongoDb PokerDemo application, closer to the final implementation, and now cooperating with the TransactionManager.