Feature/internal audit 4

[cwhinfrey]

• Add ability to pause sends to chainIds
  • Allows supported chains to be shut down
• Require TransferRoot is bonded after it is committed
  • Keeps Bonders from tricking challengers into challenging a future TransferRoot
• Only distribute relayerFee when bonding
  • Keeps outside accounts from calling withdraw and claiming relayerFee
• relayerFee -> bonderFee
  • Name change
• Add a minimum bonder fee
  • Mitigate griefing attacks from both very large sends and many small sends
• Add relayer fee for L1 -> L2 payments
  • Allows a relayer to collect a fee and recoup any L2 gas costs

[cwhinfrey]

@shanefontaine back to you