stake-contract: events

[herr-seppia]

Stake Events

• Stake
  • Emit event with the account that staked and the staked amount
• Unstake
  • Remove receiver of the withdraw, relying on the transfer contract to inform of the mint
• Withdraw
  • Remove receiver of the withdraw, relying on the transfer contract to inform of the mint
• Reward
  • Change the reward function to take a vector of keys and values, to emit a single event. Consolidate reward calls into one #2292
  • Add reason for reward - possibly a byte is enough. Consolidate reward calls into one #2292
• Slash
  • Merge the suspended and slash events into one
• Hard Slash
  • Merge the suspended and hard_slash events into one

See also #2265

[ureeves]

Very nice! LGTM