docs: function dropDb(config, dbUser, dbName, cb){
    log.logger.trace({user: dbUser, name: dbName}, 'drop database');
    
    var url = config.mongoUrl;
    var admin = config.mongo.admin_auth.user;
    var admin_pass = config.mongo.admin_auth.pass;
  
    MongoClient.connect(url, function(err, dbObj){
      if (err) return handleError(null, err, 'cannot open mongodb connection', cb);
  
      var dbToDrop = dbObj.db(dbName);
      dbToDrop.authenticate(admin, admin_pass, {'authSource': 'admin'}, function(err){
        if(err) return handleError(dbObj, err, 'can not authenticate admin user', cb);
  
        dbToDrop.removeUser(dbUser, function(err){
          if(err){
            log.logger.error(err, 'failed to remove user');
          }
          dbToDrop.dropDatabase(function(err){
            if(err) return handleError(dbObj, err, 'failed to drop database', cb);
            dbObj.close();
            return cb();
          });
        });
      });
    });
  }