Replace logging.getLogger with custom get_logger.
Remove some unneeded dependencies and reorder other.

due to remaining bits that had not been changed after a refactor.

- Resolves: #7093

- Related: #6359

This concern is addressed by the following mail pullreq, that will be
into 0.4.0 release:

https://github.com/leapcode/leap_mail/pull/175

By the way, it is really funny that I cannot tell if this comment was
written by meskio, as the blame says, or if I was the original author of
the remark. I should stop drinking so much coffee.

factory.do_Stop will handle this now.

we should deal with this with pure deferreds

From kali: add some notes about the improper handling of the mailbox
required to initialize the account, and draft some notes about how
to improve this in next iterations.