dart convert for conversions

Author: lohanidamodar

templates/dart/lib/package.dart.twig

@@ -1,6 +1,7 @@
 library {{ language.params.packageName }};
 
 import 'dart:io';
+import 'dart:convert';
 import 'package:dio/dio.dart';
 import 'package:meta/meta.dart';
 import 'package:dio/adapter.dart';

templates/flutter/lib/package.dart.twig

@@ -1,6 +1,7 @@
 library {{ language.params.packageName }};
 
 import 'dart:io';
+import 'dart:convert';
 import 'package:universal_html/html.dart' as html;
 import 'package:dio/dio.dart';
 import 'package:meta/meta.dart';