* Adds Stylelint
- New npm script, css-lint
- Pulls in Bootstrap's config
- Replaces named color with BS variable
- Updates readme with new script, also adds links to other tools
* Add css-lint script in `npm test`
* Mention Stylelint in the readme, add test to script table
* Mention npm test there too
* Explain stylelintignore and stylelintrc files
Co-authored-by: XhmikosR <xhmikosr@gmail.com>