Add the ability to push and pull on a schedule?

[gudstrand]

I would love to see the ability to push and pull on a schedule. For example, it would be great to push all my changes from one PC at 5PM and have my other PC scheduled to pull changes at 5:30PM. Also to avoid conflicts it would be great to be able to set an active window for p[ushes and pulls. For example, you could have an interval of 15 minutes but have it only run within an 8Am to 5PM window.

[Vinzent03]

I turned this into an issue #276