Adding support to run a Configserver in the same node.

To run the _Configuration Server_ in the same node we implemented the
following changes.

1. You can now define the port of the _config server_ through
`node[:mongodb][:configsvr][:port]`. It defaults to 27019.

2. When setting a _MongoS_ you can manually override the _Configuration
Server_ List by the attribute `node['mongodb']['configservers']` with
the following format:

```
"configservers" : [ { "fqdn" : "localhost", "mongodb": { "configsvr" : { "port": "27019" } } } ]
```

[ticket: X]: ?