General css organizing, Button component

[irubido]

Changes that I do on every project with starter

PR Checklist

• [x] I have run linter localy
• [x] I have run unit and integration tests locally
• [x] Rebased to master branch / merged master

Changes

-all scss files to style folder -box sizing border box -Button that extends HTMLButtonElement props with only color props, easier to customize based on project -Button accepts children instead of label

Issues

Closes #29