title: FormData upload in angular4 application
body: <p>In my angular4 application I'm trying to upload the video to server.
  But no matter what i add to the content type it always results in error from the server.
  In angular 1 the same api is hit using <strong>{ 'Content-Type': undefined }</strong></p>
  
  <p>i tried the same in angular but it dint work.
  The data and everything is correct.
  I have tried with content-type set as below</p>
  
  <pre><code>headers.append('Content-Type', 'multipart/form-data');
  headers.append('Authorization', token);
  headers.set('Accept', 'application/json');
  </code></pre>
  
  <p>and also as below</p>
  
  <p><strong>headers.append('Content-Type', undefined);</strong></p>
  
  <p>below is the http request method:</p>
  
  <pre><code>public uploadVideo(formData: any) {
  
  
          var Upload = this.baseUrl + this.ngAuth.getApiUrl('Upload');
          var authData = JSON.parse(this.localStorage.localStorageGet('token'));
          var token = 'Bearer ' + authData.token;
          var self = this;
  
          var headers = new Headers();
          headers.append('Content-Type', 'multipart/form-data');
          headers.append('Authorization', token);
          headers.set('Accept', 'application/json');
  
          return this.http.post(Upload , formData, { headers: headers, method: 'POST' })
              .map((res: Response) =&gt; res.json());
  
      }
  </code></pre>
  
  <p>Please guide!
  Thanks</p>