Implement additional Solidity CI and gas testing packages

[onggunhao]

https://medium.com/edgefund/testing-and-code-coverage-of-solidity-smart-contracts-660cb6291701

• surya
• solidity-coverage
• eth-gas-reporter
• solhint
• solidity-docgen
• Use MythX? Mithril?

Surya for graphing out contract dependencies
https://github.com/ConsenSys/surya

https://ethereum.stackexchange.com/questions/47188/what-continuous-integration-services-support-running-truffle-solidity-tests/59176

https://blog.coinfabrik.com/test-solidity-smart-contracts-using-travis-ci/

https://ethereum.stackexchange.com/questions/47188/what-continuous-integration-services-support-running-truffle-solidity-tests/59176

https://forum.zeppelin.solutions/t/test-smart-contracts-like-a-rockstar/1001