Initial setup- dev environment

[nfurfaro]

This adds the smart-contract directory, as well as some tooling and dependencies. This setup will still evolve a bit, and I'll document how to run it. TLDR:

• NO truffle
• NO ganache
• NO web3.js Buidler is the high-level task-runner, which is very configurable via plugins, tasks and scripts. It can use truffle/ganache/web3, but I've opted to use Waffle/ethers.js/buidlerEVM combo. https://buidler.dev/getting-started/

What this brings:

• Fast testing
• solidity-native console.log and full stack-traces
• sweet chai matchers for ethereum (https://ethereum-waffle.readthedocs.io/en/latest/matchers.html)

cc @julien51

[julien51]

Ship ti!

[nfurfaro]

@julien51 Looks like you need to merge this... I don't have a button ;)