title: cannot access to this of component in subscribe function
body: <p>I'm trying navigate to new page when get answer from server:</p>
  
  <pre><code>import {Component} from '../../node_modules/angular2/core';
  import {Router} from "../../node_modules/angular2/router";
  import {Http, Headers, HTTP_PROVIDERS} from '../../node_modules/angular2/http'
  
  @Component({
      selector: 'test-page',
      templateUrl:'src/login/test.html',
      providers: [HTTP_PROVIDERS]
  })
  
  
  export class TestPage {
      constructor(private _router:Router,
                  private _http:Http) {
      }
  
      Test(username, password) {
          let body = 'test';
          let headers = new Headers();
          headers.append('Content-Type', 'application/x-www-form-urlencoded');
          this._http.post('/api/test', 'test', {headers: headers})
          .subscribe(
                  response =&gt; {
                      this._router.navigateByUrl('Home'); //'this' is not a component
                  },
                  error =&gt; {
                     console.log(error)
                  }
         );
       }
  }
  </code></pre>
  
  <p>But by some reason 'this' is not a pointer to component but it's a subscribe.
  Does someone know the reason of issue?</p>