Set proposal threshold

Currently we have a threshold in place which requires 2 nouns to put a proposal on chain. The intention of the threshold is to reduce spam. For the current size of nounsDAO it is not necessary. This is a built-in threshold which can be adjusted at any time with a proposal.

Proposal to change the threshold from 2 nouns to 1 noun for putting a proposal on chain. This would allow any address with a minimum of 1 NOUN to formally propose to the DAO, until the Noun supply reaches 1000. After that the threshold will be set to 2 again.

This is an updated version of Prop 134.