fix tsconfig.json build target es6 not working issue

[vincent178]

Thanks for the great project. It helps a lot.

I found an issue when I use tsc compiler compile to target es6, the controller doesn't work.
So I dig in the source code, I found that when compile to es6, the controller class doesn't convert to function style, then the Object.keys(this.targetClass.prototype) always return blank array [].

for example

// compiler target es6 
class UsersController { 

  constructor(templateService, calendarsServer) {
    this.templateService = templateService;
    this.calendarsServer = calendarsServer;
  }

  indexAction(request, response) {
  }

  get index() {
  }

};

// compiler target es5
function UsersController1(templateService, calendarsServer) {
    this.templateService = templateService;
    this.calendarsServer = calendarsServer;
}

UsersController1.prototype.indexAction = function(request, response) {
}

const p1 = UsersController.prototype;
const p2 = UsersController1.prototype;

console.log(p1);
console.log(p2);

console.log(Object.keys(p1).length); // returns 0
console.log(Object.keys(p2).length); // returns 1

I made a PR to fix this using Object.getOwnPropertyNames refer to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties

Thanks,
Vincent

[coveralls]

Coverage decreased (-0.003%) to 99.365% when pulling f8faee8 on vincent178:master into 5d8a671 on Romakita:master.

[Romakita]

Hello Vincent178,

Thanks for your pull request :)
I have remove the ES6 compilation option for the version 1.2 because I had some issues.
I will test a little more ts-express-decorators in future releases ;)

Thanks again 👍
Romain