imgstorage: fix indentation

fix part of imgstoragenas
there is still a lot to do on this side
imgstorage: try to add tornado logging to our logging

it still does not work though :-(
imgstorage: fix leaking open FD

The runCommandBackground was leaking a file desriptor (a pipe)
every time it was invoked (it was the stdin).

This was causing a file descriptor exaustion on the long run