Small fix, but strictly it breaks the API. Committed.start config now requires
MongoNativeModule: require('mongodb')

We suspect that a problem emerges in circumstances where committed gets hold
of a different instance of the mongo-native module from whatever the mongo-
native you're using in your main application. This is possible if committed
and your application have different version numbers, or if you've done 'npm
install' inside node_modules/committed.

Handing the whole mongo-native module into committed means this shouldn't
happen.