It seems like there is an easy way to detect when a site is behind cloudflare.

This can be done by checking:

1. That the cf-ray header is present
2. That the IP is in the range of the known cloudflare IPs: http://cloudflare.com/ips

It would be useful to annotate measurements of this sort to reduce false positives especially when they are via HTTPS. If we do reach cloudflare it means that it's most likely not blocked.

This is related to: https://github.com/TheTorProject/ooni-pipeline/issues/84