Currently, we don't want to log to syslog, because the platform has to be
modified before we can do that (see #6942). In the future, we might want to
log to syslog only, or make it optional depending on the contents of
/etc/default/leap_mx. For now we just remove twistd's --syslog option from the
initscript.

Closes: #6937.

Release Leap MX version 0.7.0.

Conflicts:
	setup.py

There are some reasons to remove the initscript from the python package:

  1. To include the initscript it in the python package it is necessary to
     assume a lot of things about the system in which the package would be
     installed.

  2. The debian packaging system will correctly create an initscript by
     itself.

  3. We don't have to maintain 2 different setup.py files (one in
     master/develop branch and another in debian package branches).

Tag leap.mx version 0.6.2

Conflicts:
	CHANGELOG
	src/leap/mx/mail_receiver.py

If we do not adhere to the standads, we may have a lot of problems when
bouncing a message. This commit implements a bounce message according to:

  * RFC 6522 - The Multipart/Report Media Type for the Reporting of Mail
    System Administrative Messages

  * RFC 3834 - Do not bounce for unknown or invalid addresses.

  * RFC 3464 - An Extensible Message Format for Delivery Status Notification.

Closes: #6858.

This commit changes the bounce message sender address to be
MAILER-DAEMON@domain, instead of bounce@domain.

Related: #6858.