Document Scheduler Expiration Date Should Be Optional

When a Document Scheduler is created for a tab that has expiration dates enabled, it will automatically populate an expiration date when the tab is created, and there is no way to turn that off. Until the actual document is received, there is usually no way of knowing what the expiration date should be, leading to inaccurate or unnecessary expiration dates being added by the Document Scheduler. Having the Document Scheduler fill in the expiration date should be optional instead of mandatory.