Update css style

Brings our CSS code style guide up to date

Status: **Opened for visibility**

Reviewers: @kpeatt
Ticket: N/A
Linked PRs: Includes #12 

## Changes
- Updates preferred property sort order
- Adds tooling config for scss-lint and csscomb
- Adds info on tooling and preferred frameworks
- Adds background and attribution for our practices
- Misc fixes, e.g. broken links