Add configurable post-pomodoro hook

[Adam Coddington]

While doing a little research toward integrating Fitocracy and Motifit data into my Beeminder goals, I came across this project on Github:

• Beemodoro

Although it doesn't line-up with exactly what I'm hoping to do, it did make me consider that maybe tracking pomodoros engaged in toward the completion of specific tasks might be a useful way of improving my productivity.

Toward that end and other ends that people might have, I've decided to add a feature that kicks-off a configurable script at the end of one's pomodoro, passing (via sysargs) the UUID of the task for which a pomodoro was just completed. This will allow people to wire-up any number of things after they complete each pomodoro, including perhaps sending data to beeminder.

[Adam Coddington]

Added as part of 1.2.0