Removing "use strict" directive since ES6 modules will always be
in strict mode.

Also, webpack and other build tools will automatically add the
directive during compilation.

Remove and tidy some comments and fix broken links.

Prettier will be used to ensure coding style is consistent.

The major change is reindenting from 4 to 2 spaces.

chore: lint with prettier and update README.md

test: add benchmark test

docs(readme): add example benchmark output and script

Resolves #70

style-to-object                    0.2.1  →    0.2.2
@commitlint/cli                   ^6.1.0  →   ^7.1.2
@commitlint/config-conventional   ^6.1.0  →   ^7.1.2
coveralls                         ^3.0.0  →   ^3.0.2
eslint                           ^4.18.0  →   ^5.5.0
eslint-plugin-prettier            ^2.6.0  →   ^2.6.2
lint-staged                       ^7.1.1  →   ^7.2.2
prettier                         ^1.12.1  →  ^1.14.2

devDependencies:
* webpack@4.19.0
* webpack-cli@3.1.0

Update build and dependencies