Trigger resubmission when a submission has been removed from the issue

[jonasraoni]

At this moment, when a submission is removed from an issue, the code is not able to detect the change and resubmit the issue.

The code detects changes to the issue by comparing an internal last modified date to the last modified date of the issue and submissions assigned to it. If a submission is removed from the issue, the last modified date of the issue isn't updated, and the submission is also not checked anymore, we don't keep track of it.

• It makes sense to include all possible "last modified dates" to the existing code.
• Listening for publish/unpublish events is an option, but listening for hooks that happen before inserting/updating sounds like a better option
• The application (for now just OJS) can be updated to reflect such updates in a better way.