Update dev dependencies

Author: philwareham

package.json

@@ -20,19 +20,19 @@
     "autoprefixer": "6.3.6",
     "grunt": "~1.0",
     "grunt-cli": "~1",
-    "grunt-concurrent": "2.2.1",
+    "grunt-concurrent": "2.3.0",
     "grunt-contrib-clean": "1.0.0",
     "grunt-contrib-copy": "1.0.0",
     "grunt-contrib-cssmin": "1.0.1",
     "grunt-contrib-jshint": "1.0.0",
     "grunt-contrib-watch": "1.0.0",
     "grunt-dev-update": "2.0.0",
     "grunt-postcss": "0.8.0",
-    "grunt-sass": "1.1.0",
-    "grunt-sass-lint": "0.1.1",
-    "load-grunt-tasks": "~3.4",
-    "node-sass": "3.4.2",
-    "sass-lint": "1.5.1"
+    "grunt-sass": "1.2.0",
+    "grunt-sass-lint": "0.2.0",
+    "load-grunt-tasks": "~3.5",
+    "node-sass": "3.7.0",
+    "sass-lint": "1.7.0"
   },
   "scripts": {
     "test": "grunt travis --verbose"