Update references to EIP 820 to EIP 1820.

[MicahZoltu]

This repository has a number of references to EIP 820, when I believe it should be referencing 1820 everywhere.

[0xjac]

@MicahZoltu thanks for the report. I am currently working on an updated version which handles EIP 1820 and fixes coverage which is broken too.

I hope to be done in the next couple of days.