Support authSource authentication option in mongodb

[TheolZacharopoulos]

You can add now an authentication database for mongodb by initialising the eventstore:

var es = require('eventstore')({
  type: 'mongodb',
  host: 'localhost',                          // optional
  port: 27017,                                // optional
  dbName: 'eventstore',                       // optional
  eventsCollectionName: 'events',             // optional
  snapshotsCollectionName: 'snapshots',       // optional
  transactionsCollectionName: 'transactions', // optional
  timeout: 10000                              // optional
  // authSource: 'authedicationDatabase',        // optional
  // username: 'technicalDbUser',                // optional
  // password: 'secret'                          // optional
});

[adrai]

I will look at it tomorrow ok?
so I will update a lot of other modules too

[TheolZacharopoulos]

Great, thanks man.