Use Hugo for Sass processing (#9404)

* Move all Sass into a common /assets directory

* Remove node-sass make command

* Change head partial to accommodate full Sass rules

* Bump Hugo version in Netlify config

* Use separate partial for CSS imports

* Bump Hugo version

* Remove PostCSS from the pipeline

* Un-bump version

* Update Hugo version to 0.44

* Update Hugo version in Makefile

* Update production Hugo version

* Fix misspelled variable name

* Add ./resources folder to Git

* Update Hugo version in Netlify config to 0.45.1

* Use un-cached css.html partial

* Re-work extra CSS logic for .Params.css

assets/sass/_skin.sass

@@ -0,0 +1,25 @@
+$blue: #3371e3
+$light-grey: #f7f7f7
+$dark-grey: #303030
+$medium-grey: #4c4c4c
+$white: #ffffff
+
+$base-font: 'Roboto', sans-serif
+$mono-font: 'Roboto Mono', monospace
+
+
+*, .button
+	box-sizing: border-box
+	font-family: $base-font
+	background: none
+	margin: 0
+	border: 0
+
+body
+	font-family: $base-font
+
+h1, h2, h5, p
+	font-weight: 300
+
+h3, h4
+	font-weight: 400