Add modified gruntfile.js and tasks

tasks/options/concat.js

@@ -0,0 +1,13 @@
+// concat
+module.exports = function(config) {
+    return {
+        js: {
+            src: config.jsFilesToInject,
+            dest: '.tmp/public/concat/production.js'
+        },
+        css: {
+            src: config.cssFilesToInject,
+            dest: '.tmp/public/concat/production.css'
+        }
+    };
+};