Minimum viable product

Minimum viable product (#3)

* Created basic wizard with static navigator. Updated react dependency from 16.2 to 16.3 in order to support getDerivedStateFromProps.

* Updated tsconfig to generate declaration files automatically

* Set rollup as module bundler instead of using tsc.

* Added example project.

* Added and configured github pages to deploy example project.

* Updated license information

* Moved default wizard navigator to a separate component.

* Created wizard context and exposed consumers using render prop and higher order component APIs

* Created Wizard Navigator and Steps compound components. Provided render props API to Navigator component in order to increase flexibility.

* Moved children prop validation from render method to propTypes.

* Updated how to get the total steps number considering the implementation of Steps compound component.

* Moved totalStep calculation from getDerivedStateFromProps to constructor in order to improve performance. Refactored wizard state shape to provide boolean flags that reflects steps availability when navigating

* Added onStepChange event handler.

* Added step tracker

* Refactored project structure

* Removed Wizard's class constructor.

* Added eslint

* Refactored to comply with the ESLint rules

* Added precommit validation using git hooks

* Moved scripts.precommit to husky.hooks.pre-commit

* Updated README