Punish for execution failures

[ryscheng]

Compute nodes should be punished for wrong answers from transaction processing

[willscott]

This seems to be one of the places we're furthest behind right now. We're getting the concept of the staking token in #238. Once that's there we'll need to wire it in to all of the components.

We also need a component for how entities can get an initial stake balance transferred to them, so that they can get registered and begin work.

I think these are the remaining sub-tasks

• Compute node performs a stake / escrow when it registers with the registry
• Registry checks stake
• Client performs a stake / escrow when it makes a call
• Consensus resolves escrows
• Test utility for manual transfers that can be used to bootstrap state in testing
• p2: Wiring staking / incentives into storage
• p2: Wiring staking / incentives for contract registry

[kostko]

Replaced with #2078.