Convert Codebase Linter from JsHint to Eslint

[nyambati]

Problem

The current codebase uses Jshint linter which does not work well with ES6 configuration. With Node 8 LTS Approaching, we may need to update the codebase to supported ES6 functionalities to shake off some of the modules currently being used e.g Lodash.

Solution

Convert the current Linting configuration to use Eslint with Airbnb styleguide.