Cron Expressions that support Seconds

[prostuff16]

We had been using Quartz within our project but found Coravel and am liking it very much. I has been easier to implement.

There are a couple of things I would like to see:

1. One was already put forward as a "RunAt" that a DateTime could be passed to. I would love to see that as it would be a nice little extension to have and use.
2. An "expansion" to the Cron Scheduling so that we can have cron expressions with the ability to specify seconds, minutes, etc.