refactor url paths

no need for landing url because the index should take you there if you're logged-in
no reason to keep username in url because authentication is based on cookies and making
custom user-based urls makes things more complicated
updated index view and changed default login redirect

the index now checks if admin user is logged in and if so, will
log him out (he shouldn't be using /bw/)
the index is now shows the landing page for valid logged users