Graphql Css Versions Save

• Completely new API with support for a hook-like useGqlCSS function.
• New styled helper that accepts string literals just like styled-components/emotion
• New getStyles helper that returns an object with generated styles to be used in other CSS-in-JS libraries

Improves enterprise grade integrations and validations:

• Code formatting with prettier
• Code validation with eslint
• Complete 100% code coverage (HUGE thanks to @paulmolluzzo!)
• Codecov report (https://codecov.io/gh/braposo/graphql-css)
• Travis CI build report (https://travis-ci.org/braposo/graphql-css/)

• Adds support for variables and variant argument in GraphQL queries to extract different versions of the styles (theming)
• Updates examples with new variant option
• Updates README with examples and adds headings for better structure

• Improves README
• Fixes typo in README examples #2 (thanks @Scrum)