Added post scheduling for future dates

If a loaded post have a future date, a timer is set so that all watchers are fired
at (a few seconds after) the time of the post. This allows post scheduling to
happen automatically just by adding future dates.

This addresses issue #66 (opened by myself) in the simplest way I could think of. I haven't added any tests as watching is still untested and I really don't know how to test this. current tests pass.