Allow changing category after an issue is closed

[charlesbrandt]

Currently, if an issue is closed, it is not possible to change the category without first re-opening the issue. Re-opening could cause associated people to receive email updates about an already closed case. However, at this stage, users do not need notification that the category is being updated. (It may be the case that users don't ever need an email notification that the category is changing... open for discussion.)

It would be useful to allow changing the case category after the issue is closed. This would facilitate cleaning up mis-categorized issues for subsequent data analysis or visualization.

Here is an example of a case that is incorrectly categorized: https://bloomington.in.gov/crm/tickets/view?ticket_id=168162