Allow log disable in account/container server

Logging can be disabled in the object server, but not in the
account and container server though both sample configs already
include that setting. This patch allows to disable logging for
account and container server as well.

Functionality is ensured by some additional tests.

Closes-Bug: 1280954
Change-Id: Ia4e87911863089c3bea093d9f181ff29e9e963eb
Merge "Allow log disable in account/container server"