Use babel/-ify to generate compatible version

package.json

@@ -29,14 +29,42 @@
     "sheet-router": "^4.2.3",
     "weight-sort": "^1.3.0"
   },
+  "browserify": {
+    "transform": [
+      [
+        "babelify",
+        {
+          "presets": [
+            [
+              "env",
+              {
+                "targets": {
+                  "browsers": [
+                    "last 2 versions",
+		    "> 0.5%",
+                    "safari >= 7",
+                    "ie >= 11"
+                  ]
+                }
+              }
+            ]
+          ]
+        }
+      ]
+    ]
+  },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "build": "browserify -g browserify-css src/index.js -o dist/openstreetbrowser.js",
+    "build": "browserify -g browserify-css src/index.js -o dist/tmp1.js && babel --presets env dist/tmp1.js > dist/tmp2.js && mv dist/tmp2.js dist/openstreetbrowser.js && rm dist/tmp1.js",
     "watch": "watchify --debug -g browserify-css src/index.js -o dist/openstreetbrowser.js -v",
     "prepublish": "npm run build",
     "lint": "standard src/*.js"
   },
   "devDependencies": {
+    "babel-cli": "^6.26.0",
+    "babel-core": "^6.26.0",
+    "babel-preset-env": "^1.6.1",
+    "babelify": "^8.0.0",
     "browserify": "^14.4.0",
     "browserify-css": "^0.14.0",
     "standard": "^10.0.2",