title: Save remote img-file to server, with php
body: <p>I want to save a remote img-file to my server, but I don't know how to do.</p>
  
  <p>The image url is <code>http://img.youtube.com/vi/Rz8KW4Tveps/1.jpg</code> and <code>1.jpg</code> is to be saved and renamed to <code>imgfolder/imgID.jpg</code></p>