Adding tests for etherscan

[Ryanmtate]

No description provided.

[danfinlay]

If I remember right, these still aren't run as part of the main suite.

Do you have an opinion on that? Is it ok to add tests to the suite that are dependent on an external service?

[Ryanmtate]

I'll add tests for the main sub-providers; realize the etherscan tests may not be priority at the moment...

[Ryanmtate]

This PR also contains a file change to hooked-wallet-ethtx.js:

const self = this

Received: ReferenceError: self is not defined when calling from eth-faucet project.

//

In the future, these should be separate PRs.

[kumavis]

@Ryanmtate thanks!