Housekeeping
Avoid trying to auth empty users

This can happen when the login form is submitted for other auth types
where user is blank, such as OpenID.
Redirect to the desired next page on successful auth
No need to manually use HTTP::Request
Rip out local caching of successful passwords

Hopefully pause.perl.org is much more reliable than 7 years ago.  We can
re-add it if necessary, but this reduces complexity and means old
passwords won't continue to work between the time you change it on PAUSE
and the time you next login to rt.cpan.org with the new password.