Add qa:lint-css task, incorporate style linting into current flow

[MAILPOET-1917]

.stylelintrc

@@ -0,0 +1,8 @@
+{
+  "plugins": [
+    "stylelint-order",
+    "stylelint-scss"
+  ],
+  "rules": {
+  },
+}

RoboFile.php

@@ -59,8 +59,14 @@ class RoboFile extends \Robo\Tasks {
   function watchCss() {
     $css_files = $this->rsearch('assets/css/src/', array('scss'));
     $this->taskWatch()
-      ->monitor($css_files, function() {
-        $this->compileCss();
+      ->monitor($css_files, function($changedFile) {
+        $file = $changedFile->getResource()->getResource();
+        $this->taskExecStack()
+          ->stopOnFail()
+          ->exec('npm run stylelint -- "' . $file . '"')
+          ->exec('npm run scss')
+          ->exec('npm run autoprefixer')
+          ->run();
       })
       ->run();
   }
@@ -313,6 +319,7 @@ class RoboFile extends \Robo\Tasks {
       return $this->qaCodeSniffer('all');
     });
     $collection->addCode(array($this, 'qaLintJavascript'));
+    $collection->addCode(array($this, 'qaLintCss'));
     return $collection->run();
   }
 
@@ -324,6 +331,10 @@ class RoboFile extends \Robo\Tasks {
     return $this->_exec('npm run lint');
   }
 
+  function qaLintCss() {
+    return $this->_exec('npm run stylelint -- "assets/css/src/components/**/*.scss"');
+  }
+
   function qaCodeSniffer($severity='errors') {
     if ($severity === 'all') {
       $severityFlag = '-w';

package.json

@@ -15,7 +15,8 @@
     "lint5": "eslint -c .eslintrc.es5.json --ignore-pattern helpscout.js --max-warnings 0 'assets/js/src/**/*.js'",
     "lint-tests": "eslint -c .eslintrc.tests.json --max-warnings 0 'tests/javascript'",
     "autoprefixer": "postcss assets/dist/css/*.css --use autoprefixer --no-map --replace",
-    "scss": "node-sass assets/css/src/ --output assets/dist/css/ --output-style compact"
+    "scss": "node-sass assets/css/src/ --output assets/dist/css/ --output-style compact",
+    "stylelint": "stylelint --fix"
   },
   "dependencies": {
     "@babel/runtime": "^7.2.0",