Proposal: Consensus / Leadership "Summit"

https://www.dash.org/forum/threads/proposal-consensus-leadership-summit.14630/

This proposal funds the attendance of most of the Dash Core Team leadership to attend Consensus 2017 (including additional tickets beyond our package), to hold our first in-person core team leadership meeting, and extends an additional day to allow part of the team to attend Token Summit, an event the day after Consensus.