title: OAuth to Azure fails with invalid_grant
body: <p>I've been trying to use the Office 365 APIs Preview, but I can't get the OAuth authentication to work. </p>
  
  <p>I get to the step where I receive the code in the callback. 
  But when I try to trade the code to get a access token as described <a href="http://blogs.msdn.com/b/exchangedev/archive/2014/03/25/using-oauth2-to-access-calendar-contact-and-mail-api-in-exchange-online-in-office-365.aspx" rel="nofollow">here</a></p>
  
  <p>It fails with:</p>
  
  <pre><code>{"error":"invalid_grant","error_description":"AADSTS70002: Error validating credentials. AADSTS70000: The provided access grant is invalid or malformed.\\r\\nTrace ID: 48d94ac6-69d1-4232-96b1-158994428c25\\r\\nCorrelation ID: 2fcade34-489a-4bd5-96d3-47f7aeb3aabf\\r\\nTimestamp: 2014-05-14 21:16:24Z","error_codes":[70002,70000],"timestamp":"2014-05-14 21:16:24Z","trace_id":"48d94ac6-69d1-4232-96b1-158994428c25","correlation_id":"2fcade34-489a-4bd5-96d3-47f7aeb3aabf"}'
  </code></pre>
  
  <p>I'm using <code>grant_type=authorization_code</code>.</p>
  
  <p>Anyone know what <code>https://login.windows.net/common/oauth2/token</code> is expecting? </p>