feat(): add optional es7.classProperties transformer to Babel

Author: Awk34

app/templates/Gruntfile.js

@@ -589,7 +589,10 @@ module.exports = function (grunt) {
     // Compiles ES6 to JavaScript using Babel
     babel: {
       options: {
-        sourceMap: true
+        sourceMap: true,
+        optional: [
+          'es7.classProperties'
+        ]
       },<% if(filters.babel) { %>
       client: {
         files: [{

app/templates/karma.conf.js

@@ -43,7 +43,10 @@ module.exports = function(config) {
 
     babelPreprocessor: {
       options: {
-        sourceMap: 'inline'
+        sourceMap: 'inline',
+        optional: [
+          'es7.classProperties'
+        ]
       },
       filename: function (file) {
         return file.originalPath.replace(/\.js$/, '.es5.js');