Match circuitID field for Scheduled Maintenance

Currently the best way we can think of to do scheduled maintenance on a per circuit basis is to create a group that matches the circuitID for the service in question and then use that group for the associations in the maintenance window.

If we could simply enter a list of circuit IDs that would save us needing to create thousands of groups to identify individual circuits, any combination of which could be affected by upstream supplier maintenance windows, or our own maintenance windows.