Expose Scheduler Option

[lockhartja]

@sksamuel first awesome library -- thanks for the effort it took to make this available to the community. I was wondering if there currently exist a way to expose the scheduler option the original library has documented?

[sksamuel]

@lockhartja What do you think to this PR. https://github.com/sksamuel/aedile/pull/15 Adding a scheduler option, where you pass in a function which returns a Deferred.