marcio.js

login(obj) {
  this.postRequest('http://localhost:8888/api/student_auth/login', obj).subscribe(
	  function(result) { console.log('result', result); }
   );

  // Não vai funcionar porque o callback acima do subscribe é assíncrono
  // return result;
}

postRequest(url, data) {

  this.headers = new Headers();
  this.headers.append('Content-Type', 'application/x-www-form-urlencoded');
  //this.headers.append("Content-Type", 'application/json');          
  //this.headers.append("Authorization", 'Bearer ' + localStorage.getItem('id_token'));

  this.requestoptions = new RequestOptions({
    method: RequestMethod.Post,
    url: url,
    headers: this.headers,
    body: JSON.stringify(data)
  });

  let getObs = this.http.request(new Request(this.requestoptions))
    .map((res) => {
      return res.json()
  });
  getObs.subscribe(
      data => { 
        if(data.success) {
          this.setTokenLocalStorage(data.token);
        }
      },
      err => {
        return false;
      },
      () => console.log('done')
    );

  return getObs;

 }