Version 2.4.0 Release

Version 2.4.0 contains the following change:

• append: True can be added to a user in order to indicate that the user should be added to the sftp_group_name group, instead of having that be the only group that the user belongs to (which is currently the default behaviour). Version 3.0 might make append the default behaviour (not decided yet). Thanks to @jpiron for the contribution :-)