title: SDWebImage says "URL not found" although it exists
body: <p>I want to download an image from the web and set it as marker icon on a map. For downloading I am using the SDWebImage library. Unfortunatly I always get an error that says:</p>
  
  <pre><code>The requested URL was not found on this server.
  </code></pre>
  
  <p>But the URL exists. I tried different image URLs, everyone can be opened in the browser but I get always the same error.</p>
  
  <p>This is my code:</p>
  
  <pre><code>let url=NSURL(fileURLWithPath:"http://blogs.taz.de/arabesken/files/2012/05/testbild-sendepause-300x240.jpg")
  
  var managerCompletedBlock:(UIImage!, NSError!,SDImageCacheType,Bool) -&gt; Void = {
                        image,error,cacheType,finished in
                        if(finished){
                              if let s = error.localizedDescription
                              {
                                   println(s)
                              }
                         }
        }
  var imgManager:SDWebImageManager = SDWebImageManager.sharedManager()
  imgManager.downloadWithURL(url, options: SDWebImageOptions.HighPriority, progress: nil, completed: managerCompletedBlock)
  </code></pre>
  
  <p>I have internet connection (API calls are working) and the URL exists. Furthermore the code works as intended if I use an File Path instead of an Web URL.</p>
  
  <p>Does anybody have an idea what's the problem?</p>