preserve session when logging into fbConnect.  So existing user accounts may be mapped to facebook ids

Fixes to account creation.  avoid creation when facebook cookies are bogus. avoid expensive call when tracking user activity.

and disable drupal cache when using facebook sessions

introduced 'primary' fb connect app.

Removed debug output.

Changes to fbConnect session management.  Changing session id when logged in via fb connect.  This prevents the Drupal session from conflicting with the fbconnect session, and ensures user is properly logged out when user logs out of facebook.