Improve update of source costing statistics

It is very important that we support the ability to update source statistics at runtime. This is important due to the changing nature of read/write sources and differences between a development data source and a production data source.

The following options should be possible:

1) Update model/source statistics on VDB deployment.
2) Update model/source statistics on connector startup.
3) Update model/source statistics on at a scheduled time.
4) Update model/source statistics upon a manual request.

case 5920