ActiveRecord::Base#destroy should write 1 line into log

Currently SELECTs, INSERTs and UPDATEs generates exactly one line in the log. But DELETEs are logged in 3 lines, because the template for DELETE statements is written using heredocs. It's not convinient to read, nor to parse.

So now it is:

User Load (0.000362)   SELECT * FROM `users` WHERE `id` = 1
User Update (0.00050) UPDATE `users` SET `enabled = 0 WHERE `id` = 1
User Destroy (0.000333)    DELETE FROM `users`
 WHERE `id` = 1

Some other statement

With patch, it would be:

User Load (0.000362)   SELECT * FROM `users` WHERE `id` = 1
User Update (0.00050) UPDATE `users` SET `enabled = 0 WHERE `id` = 1
User Destroy (0.000333)    DELETE FROM `users`WHERE `id` = 1
Some other statement

So there is a patch and a test for it. Test is a little bit awkward, because I don't know any clean way to test log in Rails.