Fix Webpack issue that breaks with TypeScript

Adding noEmitHelpers to TypeScript avoid the creating of the __extends() function which breaks WebPack.

Read more: 
NativeScript/nativescript-dev-webpack#8
http://stackoverflow.com/questions/36556772/webpack-and-typescript-extends

Author: leocaseiro

tsconfig.json

@@ -4,7 +4,8 @@
         "module": "commonjs",
         "removeComments": true,
         "experimentalDecorators": true,
-        "sourceMap": true
+        "sourceMap": true,
+        "noEmitHelpers": true
     },
     "files": [
       "demo/node_modules/tns-core-modules/tns-core-modules.d.ts",
@@ -13,4 +14,4 @@
       "pulltorefresh.ios.ts"
     ],
     "compileOnSave": false
-}
+}