updated; driver to 1.3.23

As a side-effect, mongodb no longer passes the stats as a third
argument to a mapReduce callback unless the verbose option is set. To
provide backwards-compatibility, we will set it unless it is explicitly
unset.

I am mostly interested in this update for this change which resolves
pending commands with errors on a manual disconnection:

https://github.com/mongodb/node-mongodb-native/commit/2667d13214dc6ef80e68aa5e57dc56739a7fdc79

This passes all tests for me including 2.4, shard, and replica set tests.