I know how to add custom headers to alamofire request, but is it possible to add custom headers to alamofire download ? Also, how to change the file extension that is being saved in the filepath ?

```
Alamofire.download(.GET, myURL, { (temporaryURL, response) in
      if let directoryURL = NSFileManager.defaultManager()
        .URLsForDirectory(.DocumentDirectory,
          inDomains: .UserDomainMask)[0]
        as? NSURL {
          let pathComponent = response.suggestedFilename

          return directoryURL.URLByAppendingPathComponent(pathComponent!)
      }
      return temporaryURL
    }).response{ (_,_, data, err) -> Void in
      println(data)
    }

```