title: Run a script at a special time on django server
body: <p>I have a django project and i need the ability for executing a function at a specified time on django server.
  for example you can consider that in my django project if a client request for friendship to another person if after (say) 7 days that person doesn't answer that request the request will be automatically removed.
  so i want the ability of calling a function on django server at a specified time
  that is stored in mysql table.</p>