Take the delivery status from the last delivery attempt
New method PostfixLogLine#delivery_status
Extract method for dsn class and change delivery_status to hard/soft bounce
Make old method use new method
New method Delivery#status
Refactor old methods to use new methods
Add untested status method
Now calculate and store a more complete picture of the email status
Add index
More finally divide the stats shown
Show the full delivery status in the interface
Right align numbers
Different colours for soft and hard bounces