list_records: deleted count & basic auth -support

Created by: yytosi

Now that the OAI-PMH supports deleted records, it would be nice to get the deleted record count as output.

Also since CESSDA uses authentication in front of their development instance, it would be good to support basic-auth. Tornado supports it out-of-the-box, so implementing it requires only to read command line arguments and pass them to tornado’s client.