upgrading BSON

BSON 0.1.9 seems to have some sort of disagreement with the way node-mongodb-native (>1.3.9, since 1.3.8 is the last version the same BSON version used here is used) handles dispatching a Model.prototype.save() call.  You can do Model.prototype.collection.insert() instead as a workaround, but it'd be nice to have save() working.  Anyway, upgrading BSON seems to do the trick.  Unit tests pass.