Add acceptance tests for ZK games

[ajsutton]

• Proposer creates a valid proposal, verify it is not challenged
• Proposer creates a valid proposal and it is challenged, verify a proof is provided
• Invalid proposal created, verify it is challenged
• Verify the challenger resolves games correctly
  • Challenge deadline expires
  • Proving deadline expires
  • Parent is found to be invalid
  • Proven before challenge deadline expires
  • Proven before proving deadline expires