Replace gulp-sass-lint with gulp-postcss / stylelint

lib/config.js

@@ -39,6 +39,9 @@ const buildSakeConfig = () => {
     // as environment variables, as this makes more sense - ie whether you want to use browsersync or not is specific tp your local
     // dev environment and workflow, not to a particular repo.
     tasks: {
+      lint: {
+        stylelintConfigFile: null // will use the default bundled one
+      },
       makepot: {
         reportBugsTo: 'https://woocommerce.com/my-account/marketplace-ticket-form/',
         domainPath: 'i18n/languages'

lib/lintfiles/.stylelintrc.json

@@ -0,0 +1,26 @@
+{
+  "extends": [
+    "stylelint-config-standard-scss"
+  ],
+  "rules": {
+    "max-nesting-depth": 4,
+    "selector-class-pattern": null,
+    "alpha-value-notation": null,
+    "color-function-alias-notation": null,
+    "color-function-notation": null,
+    "property-no-vendor-prefix": null,
+    "scss/dollar-variable-colon-space-after": null,
+    "scss/double-slash-comment-empty-line-before": null,
+    "scss/load-no-partial-leading-underscore": null,
+    "scss/load-partial-extension": null,
+    "declaration-block-no-duplicate-properties": null,
+    "declaration-block-no-redundant-longhand-properties": null,
+    "declaration-empty-line-before": null,
+    "font-family-name-quotes": null,
+    "font-family-no-missing-generic-family-keyword": null,
+    "length-zero-no-unit": null,
+    "media-feature-range-notation": null,
+    "rule-empty-line-before": null,
+    "shorthand-property-no-redundant-values": null
+  }
+}