module keccak doesn't compile on node 12

[vird]

related cryptocoinjs/keccak#10
And probably ethereum tx sign should be in separate module

[swansontec]

I have been using Node 12 too, but fortunately the keccak dependency is optional, so both NPM and Yarn are able to install edge-core-js cleanly.

There are similar problems installing edge-currency-accountbased on Node 12, but those ones are more serious and actually prevent the install from going through. We have been able to work around those using Yarn's resolutions field to force things, like "resolutions": { "scrypt.js": "0.3.0" }. A similar technique may be helpful here if this issue is preventing progress.

I agree that Ethereum signing needs to be its own module, but some dapps using our web SDK are using it, and expect to find it on the account object. Paying off this particular bit of tech debt will be tricky, but it has been on my mind for a while. It would save a lot of space on our bundle size.