mailhandler 6.x-2.4

Known issue: #1408322: Missing data when importing multiple messages

Changes since 6.x-2.3:

• Fixed broken tests.
• Code style cleanup and refactoring.
• Changed title of mailbox name field.
• #1380868 by Dane Powell: Fixed errors on upgrade from 1.x.
• #1343630 by Dane Powell: Changed 'Mailhandler Default' to 'Mailhandler quick-start' and improved usability.
• Simplified authentication options on source nodes, added default commands for anonymous users, added more tests.
• Moved Tokenauth authentication into separate module.
• #1376784 by Dane Powell: Added default settings for mailboxes.
• Fixed broken imports.
• #1376460 by Dane Powell: Fixed machine name for mailbox not generated when copy/paste is used.