use babel-preset-latest

.gitignore

@@ -1,6 +1,9 @@
+.DS_Store
+
 # Node.js
 node_modules/
 npm-debug.log
+npm-debug.log*
 
 # jupyter
 notebooks/**/.ipynb_checkpoints/

package.json

@@ -49,7 +49,7 @@
     "babel-loader": "^6.2.5",
     "babel-plugin-transform-class-properties": "^6.11.5",
     "babel-plugin-transform-object-rest-spread": "^6.8.0",
-    "babel-preset-es2015": "^6.14.0",
+    "babel-preset-latest": "^6.14.0",
     "http-server": "^0.9.0",
     "standard": "^8.0.0",
     "webpack": "^2.1.0-beta.22"
@@ -68,7 +68,7 @@
   },
   "babel": {
     "presets": [
-      "es2015"
+      "latest"
     ],
     "plugins": [
       "transform-class-properties",