v0.6.0 Does not include focus variants

[deanmraz]

Issue

• v0.6.0 is missing the focus variants https://tailwindcss.com/docs/functions-and-directives/#variants
• https://github.com/embermap/ember-cli-tailwind/blob/v0.6.0/blueprints/ember-cli-tailwind/files/__root__/tailwind/config/tailwind.js
• No other version to use from NPM.

Expected

• https://github.com/embermap/ember-cli-tailwind/blob/master/blueprints/ember-cli-tailwind/files/__root__/tailwind/config/tailwind.js