title: Using http.put() results in: '400 Bad Request for URL exception'
body: <pre><code>update(url: string, data: Object): Promise&lt;Application&gt; {
      return this.http
          .put(url, JSON.stringify(data), {headers: this.headers})
          .toPromise()
          .then(() =&gt; data)
          .catch(this.handleError);
  }
  </code></pre>
  
  <p>Using the above function with a valid URL results in the following exception:</p>
  
  <pre><code>EXCEPTION: Uncaught (in promise): Response with status: 400 Bad Request for URL: null
  </code></pre>
  
  <p>I am using the <code>@angular/http</code> module to perform the request.
  The strange thing about this problem is that other methods of the module work fine (<code>GET</code>, <code>POST</code> and <code>DELETE</code>).   </p>
  
  <p>I am using the following header <code>'Content-Type': 'application/json'</code> and the <code>InMemoryWebApiModule</code> to mock a response.</p>
  
  <p>Calling the put function with a hard-coded value such as the following example results in the same exception.</p>
  
  <pre><code>this.http
          .put('app/applications/1', JSON.stringify(data), {headers: this.headers})
          .toPromise()
          .then(() =&gt; data)
          .catch(this.handleError);
  </code></pre>