[atlas] Probe operator notifications

(Seeing the thread about DNS intercepted probes reminded me to send this:) For 5 or so years running I have a probe operating in my garage (behind my home’s NAT and using the ISP’s NXDOMAIN rewriting, non-DNSSEC handling recursive server) a run-of-the-mill home cable set up. When I got my November report, it said I’d been down the last half of November. That was news to me. I then down'd/up’d it and it reconnected and seems to be on-line again. I do get the “your probe went off-line” notices. I would like “your probe came back on-line” notices as well. If we had those, I may have noticed it stayed down after the last message I saw. Ed