Updates to cw3 spec

[ethanfrey]

When testing cw3-flex, I found a few issues in the spec, where it assumes the state of the contract (current group) is equivalent to the state of the proposal. But for dynamic groups, we need a few more queries to get all relevant data:

• QueryMsg::Proposal/ListProposal/ReverseProposal - include threshold here - the total weight can be different than that returned by QueryMsg::Threshold
• QueryMsg::Vote returns Option<Vote> including the yes/no/abstain/veto given. However, to display this correctly we need to know the voting weight of the given voter at the time it was recorded (which can be different than current weight). VoteResponse needed the weight field from VoteInfo.

[ethanfrey]

Closed by #188