Merge pull request #2219 from mozilla/issue2183-hotfix

Fix "IE doesn't keep you logged in between restarts (or page reloads)" p...

Without P3P headers set, IE is still capable of sending any existing cookies with requests to the backend.  Since cookies are sent, the authentication cookie is sent with session_context.  session_context will properly say whether the user is authenticated or not.  If the user is authenticated, emails & certs will be synced.  Any expired certs will be erased and re-certified if needed.

I give this an r+.