Prototype of system for probe URL selection

[hellais]

We started discussions around URL testing strategies during our January 2018 community meeting, during which we defined some high level goals. These include optimizing the value of collected measurements, ensuring regular testing of the same URLs for consistency, and ensuring that the tested URLs are relevant to OONI Probe users.

As part of this activity, we will define the goals and principles that we shall follow when doing URL prioritization. We have already started to think about this as part of our URL measurement policy for the OONI Probe Orchestration System. We will then build a prototype of the URL selection system and deploy it with some small subset of active probes to learn how well it works and fine tune it accordingly.

[hellais]

We have implemented and are now deploying in production the prototype. This activity has been completed. Future work is tracked in the beta quality epics: #313 & #314