update deps, fix build with node v10

package.json

@@ -5,20 +5,21 @@
   },
   "devDependencies": {
     "autoprefixer": "^6.3.3",
-    "grunt": "^0.4.5",
+    "dart-sass": "^1.16.1",
+    "grunt": "^1.0.3",
+    "grunt-bower-install-simple": "^1.1.2",
     "grunt-check-dependencies": "^0.6.0",
     "grunt-contrib-clean": "^0.6.0",
     "grunt-contrib-connect": "^0.8.0",
     "grunt-contrib-copy": "^0.5.0",
     "grunt-contrib-cssmin": "^0.12.2",
     "grunt-contrib-requirejs": "^0.4.4",
-    "grunt-sass": "^1.1.0",
-    "grunt-postcss": "^0.7.2",
     "grunt-contrib-uglify": "^0.5.1",
     "grunt-contrib-watch": "^0.6.1",
     "grunt-eslint": "^10.0.0",
-    "grunt-bower-install-simple": "^1.1.2",
-    "grunt-git-describe": "^2.3.2"
+    "grunt-git-describe": "^2.3.2",
+    "grunt-postcss": "^0.7.2",
+    "grunt-sass": "^3.0.2"
   },
   "eslintConfig": {
     "env": {

tasks/build.js

@@ -59,7 +59,8 @@ module.exports = function(grunt) {
     sass: {
       options: {
         sourceMap: true,
-        outputStyle: "compressed"
+        outputStyle: "compressed",
+        implementation: require("dart-sass")
       },
       dist: {
         files: {