Add Airbnb ESLint Config

[michael-martin]

Started on branch: https://github.com/DeloitteDigitalUK/react-redux-starter-app/tree/eslint-config

Airbnb config has several dependencies which are not not yet compatible with ESLint 3.0. This is blocked until these are resolved.

Progress is tracked on: #71 Update eslint to version 3.0.0

[michael-martin]

Quick update on this. The last outstanding blocker is eslint-plugin-react, which is nearly there! :)

I hope to publish an RC before friday and the final this week-end if there is no major issue.

jsx-eslint/eslint-plugin-react#686