Add michagogo to gitian download scripts #3023

Something seems to be wrong with the previous pull request (#2818), so I'm recreating -- see there for message and discussion.

$ gpg --list-sigs 9692B91BBF0E8D34DFD33B1882C5C009628ECF0C
pub   2048R/82C5C009628ECF0C 2013-05-23
uid                          Michagogo <michagogo@server.fake>
sig 3        82C5C009628ECF0C 2013-05-23  Michagogo <michagogo@server.fake>
sub   2048R/BC00347E7874C406 2013-05-23
sig          82C5C009628ECF0C 2013-05-23  Michagogo <michagogo@server.fake>

I'd be more comfortable if your key at least had some signatures on it, and/or you had some git commits in the Bitcoin git repository that were signed by your key. (via git commit -S) You should also have your full name on the key and a real contact email.

As it stands a third-party like myself has no evidence that you're actually a person.

@petertodd Nobody has signed git commits in our repos right now...

I agree with the name/email, though I don't think it defines who you are as a person. ;)

@luke-jr I have: git log --show-signature | grep Good\ signature

Discussed it with michagogo on IRC: we think setting weight=1 is reasonable, and would allow setting "minimumweight=121" to say that a build requires three core devs + 1 additional sig. (or something similar)

@gavinandresen When you said it should be eleven, was that serious? Was there an actual reason behind that?