Adds other hints to README

Things like reminding to kill the server or ability to start the server
in JSON-Verbose.

Adds custom Transit write handler for attendee

Part of that is definition of new constructor.

Adds additional debugging options

Server dumps database at the beggining. It recognizes verbose flag to
turn on verbose format for that initial dump.

Adds basic attendee API and persistency

Supported actions are list, index, create and update on attendee
resource.