* Replace /session/new with /login and /session/sign_out with /logout.
* Rename 'sign in' to 'login'.
This changes are to make urls cleaner and terminology more consistent.
Remove the "Remember" checkbox from the login page. Make session cookies
permanent instead. Phase out legacy `user_name` and `password_hash` cookies.
Previously a user's session cookies would be cleared whenever they
closed their browser window, which would log them out of the site. To
work around this, when the "Remember" box was checked on the login page
(which it was by default), the user's name and password hash (!) would
be stored in separate permanent cookies, which would be used to
automatically log the user back in when their session cookies were
cleared. We can avoid all of this just by making the session cookies
themselves permanent.
Fineprint text was variously styled with `.info`, `.tn`, `.hint`, or
`.cost-footnote` css classes. Standardize on `.fineprint` instead. Use
`.hint` only for form hints and `.tn` only for <tn> tags in translation
notes.
Incidentally changes the font size of form hints to 0.8em (was 0.7em)
and the color of fineprint to #888 (was #AAA or #666).
