Display Signup: Scheduler: Close date only when Signup: Scheduler: Status: Enabled

Issue Summary

On my signup_available_signups view, I'd like to display the date that the signup closes *only if* signup scheduler is enabled for that node.

Currently, the scheduler open and close dates are populated (with now()) when a signup is created, whether or not scheduler is enabled for that node, and this value is displayed when the close date field is added to the view.

I don't know if the best solution is to change what happens at the beginning - when the open/close dates are created for each signup, or at the end - when the close date is displayed regardless of the scheduler status.