Add a cron job that removes duplicate entries from the mail_message_tags table

[miaulalala]

Feature Request

Since we don't remove any data on account deletion from the mail_message_tags table, duplicate entries are more than likely.

Summary

Write a cron job that once a day cleans up all duplicate entries for mail_message_tags

[ChristophWurst]

(requires #4665 to be done ;-) )