Add eth gas reporter

[felix2feng]

Really cool that it adds gas usage after each unit test

[coveralls]

Pull Request Test Coverage Report for Build 1160

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 1154:	0.0%
Covered Lines:	321
Relevant Lines:	321

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💛 - Coveralls

[asoong]

I wonder if we can make this run for tests only and not coverage