Fix typos in httpGet error handling, add timeout, and add https

"precondition" means it's the caller's fault, which doesn't seem right. I think what we want is nature = "localBug" (which really means "callee's fault" -- maybe I should improve the terminology), and durability = "overloaded" (because if the server simply isn't responding fast enough, retrying could work, but if the problem is that the server is getting too much traffic, then retrying could make things worse).