Transpile to es5 to support older node versions

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@biesbjerg/ng2-translate-extract",
-  "version": "0.2.8",
+  "version": "0.2.9",
   "description": "Extract strings from projects using ng2-translate",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",
@@ -39,7 +39,7 @@
   },
   "homepage": "https://github.com/biesbjerg/ng2-translate-extract",
   "engines": {
-    "node": ">=6.9.0"
+    "node": ">=4.3.2"
   },
   "config": {},
   "devDependencies": {

tsconfig.json

@@ -5,7 +5,11 @@
         "noImplicitAny": true,
         "removeComments": true,
         "declaration": true,
-        "target": "ES6",
+        "target": "es5",
+        "lib": [
+            "dom",
+            "es2015"
+        ],
         "module": "commonjs",
         "outDir": "./dist/",
         "sourceMap": true