Integrate automatic talk scheduling (by copy pasting optaplanner-example's conference scheduling code)

[ge0ffrey]

For Devoxx BE 2018, Red Hat summit 2018 and Voxxed Zurich 2018, we scheduled talks to room and timeslots automatically - under many constraints such as speaker availability. Here's a video explaining what we did:
https://www.youtube.com/watch?v=GnnMHkY6vKk

This used OptaPlanner (apache license, 100% java, but also scala friendly), and the example code of optaplanner-examples's conference scheduling app. That swing app works well, and uses the REST API of cfp-devoxx, but a several conference organizers have asked why it's not integrated into the cfp-devoxx webapp itself, for convenience. So by creating this issue, I hope someone wants to pick up this work. I am happy to answer any questions. The ConferenceSchedulingApp example code can be copy-pasted or used an inspiration as you see fit.

The major missing screen in cfp-devoxx would be to fill in speaker unavailability timeslots.

[ge0ffrey]

Workaround: https://www.youtube.com/watch?v=ykF8DjxhQJI