title: Send access token without using parameter in URL
body: <p>I am developing an API using Codeigniter and Oauth2 (Alex Bilbies library). 
  The API is being used by my iPhone app. For every request I need to send along the access token as a parameter in the URL. Is there a way to send the token in a header instead? To avoid it getting "exposed"?</p>
  
  <p>Thankful for all input!</p>