Crash reporting from vere

[jalehman]

We currently have no quantitative measure for how stable Urbit is. Having the runtime submit a report of some kind to a server when it crashes, even if light on details, would allow us to begin measuring exactly how frequently crashes occur. It would be great to know what kind of crash occurred as well, but even knowing that a crash happened would be useful.

This is the kind of feature that should be opt-in, e.g. with a runtime flag. We could cover a large portion of the running Urbit fleet by working with hosting providers to turn this on.