Add eslint-shakacode-config

[aaronvb]

Fixes #228

[justin808]

Thanks @aaronvb.

Are you sure we picked up any differences in the linter setups?

[aaronvb]

@justin808 Which setups? Airbnb and the shakacode config?

[justin808]

1. Ensuring that we're using any overrides from the shakacode config on npm.
2. We should possibly update the shakacode one to depend on the latest airbnb one.

[aaronvb]

@justin808 I tested and confirmed that is it adding the override configs from the eslint-shakacode-config, although right now there aren't any overrides. Also, the eslint-shakacode-config extends the airbnb config.

[justin808]

@aaronvb This file has the override: https://github.com/shakacode/style-guide-javascript/blob/master/packages/eslint-config-shakacode/rules/react.yml

Then again, that might not affect this project.