Move vendor prefixed properties before the unprefixed ones.
Use the shorthand font property when possible.

Conflicts:
	site/_includes/css/style.css
Be explicit with the `background` property.
Remove units from zero.
Remove duplicate properties.
Add fallback colors.
Add missing vendor prefixed properties.
Simplify selectors.
Add :short_year to url_placeholders
Add short_year description to /docs/permalinks/
Have separate methods for all docs and just the docs that are being written.
Add documents to site payload
Refactor docs_to_write
Update history to reflect merge of #2297 [ci skip]
Add Deprecated articles keeper plugin
Write test for site.documents.
Merge pull request #2301 from TheTomThorogood/short_year_permalink
Update history to reflect merge of #2301 [ci skip]
Merge pull request #2300 from kzykbys/myPluginDescription
Update history to reflect merge of #2300 [ci skip]