title: Angular 2 / Typescript: For loop with HTTP request issue
body: <p>I have a HTTP get request that use a book name in url to find a price for the book.
  I added a loop to get all the prices of the books added to to array. But it seems like the next iterations don't go through. Books[0] works fine and price are added from the API. </p>
  
  <p>When I try to log the iterations, it also stops after index 0. </p>
  
  <pre><code>books: {  name: String, price: String} [] = [
      { "name": "dash", "price": "N/A" }
      { "name": "tash", "price": "N/A" }
      { "name": "mash", "price": "N/A" }
  ];
  
  getti() {
      var i: number;
      for (i = 0; i &lt; this.books.length; i++) {
          console.log(i);
          return this.http.get(url+this.books[i].name)
              .map(res =&gt; {
                  if (res)
                      this.books[i].price = res.json();
            });
      }
  }
  </code></pre>