add extra logging to the host submitting storage proofs

adds information that will potentially be helpful in #1102 (closed)

@VoidingWarranties reported that this failure was occurring frequently for him. I can't reproduce it frequently, but the one time I was able to trigger it I didn't have enough logging information to get to the bottom. For me, it happens maybe 1-in-50 tries. With this debugging information, I should be able to get farther next time I see the failure.