Prop 251: Increase minimum proposal deposit to 2 million Graviton

The current minimum deposit for a governance proposal is 100k Graviton or about ~$30 at the current price. This is insufficient to prevent spam proposals that direct users to install viruses or other malicious behavior. While no spam has been submitted in some time, governance activity tends to trigger spammers who hope to exploit users looking at legitimate proposals. This is especially concerning given that some proposal viewing software automatically renders images, providing a potential attacker with the ip address of everyone who even viewed the proposal. In order to provide better protection for the Gravity community this proposal if passed will set the governance min deposit to 2 million Graviton ~$600 at the current price. This will hopefully be sufficient to prevent spam proposals.