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

@@ -7,7 +7,8 @@
         "removeComments": true,
         "noLib": false,
         "preserveConstEnums": true,
-        "suppressImplicitAnyIndexErrors": true
+        "suppressImplicitAnyIndexErrors": true,
+        "noEmitHelpers": true,
     },
 
     "filesGlob": [
@@ -18,4 +19,4 @@
     "exclude": [
         "./platforms/**/*.ts"
     ]
-}
+}