fixing import for SafeERC20 and IERC20;
set up constructor for synthetix connector to set address for staking contract;
created MockSynthetix.sol for test;
added nomiclabs/buidler;
fixed test for SynthetixProtocol.js;
adding .gitatributes to highlight solidity on GitHub;
adding buidler artefacts and cache to git ignore;
adding buidler.config.js;
adding @openzeppelin/test-helpers, ganache-cli;
fixing test/CurveProtocol.js to pass;
added truffle network for tenderly proxy;
added .nvmrc to set to node v12 as ganache-cli requires;