enable eslint for browser code

[christophgysin]

Don't disable eslint globally, and fix issues where needed.

[DavidWells]

This will break in older browsers. Might need to hold off on merging this until let and const are supported across the board

[christophgysin]

In that case I will make eslint check browser code against an earlier ECMA version. What is considered available in browsers these days?

[christophgysin]

I updated the commit to disable the rule no-var.

The code in aws-node-auth0-custom-authorizers-api/frontend/app.js was already using const, so I left it as is.

But since these are examples used by serverless developers, supporting old browsers might not be necessary at all...

[kaihendry]

Sorry for the bike shedding, though can I put a vote in instead for the simpler https://www.npmjs.com/package/standard ?

[DavidWells]

We need to make the linting nicer... That is for sure.

I do like standard but it's different than other serverless repos.

I'm going to take a pass at the eslintrc here and relax some of the pedantic rules that require all these damn comments.

Has anyone used https://github.com/jlongster/prettier or https://github.com/kentcdodds/prettier-eslint ?

[christophgysin]

Should we open a new issue for the discussion around a new coding style?

What shall we do with this in the meantime? Close and abandon or merge until we come up with something better?

[nikgraf]

@DavidWells haven't tried Prettier yet. Will give it a try this week and can report back then.

The PR looks good to be merged now from my perspective. Any objections to merge it?