Fixed some of the login issues.
- Now use FB Javascript-SDK to handle all login. It calls a popup if the user
  is not logged in, creates a cookie if one does not exist, and generates and
  passes an access token to friendbox.php.
- XXX Uncovered a problem in firendbox.php: with the new authentication-
  through-jsSDK scheme, friendbox is throwing an exception about curl not
  supporting https. This is the next thing to fix.
- Added some documentation to friendbox mostly and index a little. Will
  need to review code formatting again in the near future.