title: BackgroundTransferService Ram Issue
body: <p>I have some doubt about BackgroundTransferRequest RAM efficiency, or more probably, I'm missing something.</p>
  
  <p>BackgroundTransferRequest should initialize a web request (GET by default) and then store the response to IsolatedStorage specified by DownloadLocation, so we shouldn't have any stream opened containing the result, we just have the physical file in the IsolatedStorage.</p>
  
  <p>Simple, Easy, Efficient.</p>
  
  <p>Then, why after 200 succeeded Downloads I still have 42k occupied ram? </p>
  
  <p>Of course If I restart the application I have 1k occupied ram and previously downloaded files are still on the Isolated Storage, so we probably have something on the BackgroundTransferRequest that occupies ram and never free it, despite the dispose call.</p>
  
  <p>Please correct me If I'm doing something wrong.</p>
  
  <p>Below you can see the code snippet used for adding and removing transfers.</p>
  
  <p><strong>INITIALIZING TRANSFER</strong></p>
  
  <pre><code>                BackgroundTransferRequest transferRequest = new BackgroundTransferRequest(transfer.TransferUri);
                  transfer.RequestId = transferRequest.RequestId;
                  transferRequest.DownloadLocation = transfer.DestinationUri;
                  transferRequest.TransferPreferences = TransferPreferences.AllowCellularAndBattery;
                  BackgroundTransferService.Add(transferRequest);
  </code></pre>
  
  <p><strong>ONCE DONE, REMOVE TRANSFER</strong></p>
  
  <pre><code>                 BackgroundTransferRequest transferToRemove = BackgroundTransferService.Find(transferID);
                  if (transferToRemove != null)
                  {
                      BackgroundTransferService.Remove(transferToRemove);
                      transferToRemove.Dispose();
                      transferToRemove = null;
                  }
  </code></pre>
  
  <p>Thanks you very much!</p>