Upgrade Ethereum Mainnet

[Tommytrg]

• Upgrade Ethereum Mainnet to v2
• Deploy the randomness in Ethereum Mainnet

[guidiaz]

WSB v2.0.15 deployed and verified into etherscan.io.

[guidiaz]

Legacy WRB@0x9E4fae1c7ac543a81E4E2a5486a0dDaad8194bdA upgraded to v0.7.18, and verified into etherscan.io.

[guidiaz]

Settled proper SLA params in legacy WitnetRandomness@0x894907c7Ab64C1092620B5c8Ba039BB6E611eba8 (v0.6).

[guidiaz]

Legacy WRB v0.7 bypassed to WitnetOracle v2.0, and verified into etherscan.io.

[guidiaz]

Recovered ethereum:mainnet stack into AWS and DFE.

[guidiaz]

Smoke tests:

• Randomize on WRv2: https://etherscan.io/tx/0xe44fd5220caddcdea2ea0b94879b558aef7c77f10d555a8925f299254d62ffe1
• Randomize on legacy WR: https://etherscan.io/tx/0x2e535b9e3f2ac8094aa02248af95a91693e010c8f2592c5b19091e867b36e97b

[guidiaz]

Related PRs:

• https://github.com/witnet/witnet-solidity-bridge/pull/435
• https://github.com/witnet/witnet-solidity-bridge/pull/436
• https://github.com/witnet/data-feeds-explorer/pull/424
• https://github.com/otherplane/bridge-iac/pull/201