Initial work on resetting forgotten passwords. It works, but still need to email a token to allow reset

The search box style is a design decision, search boxes are always styled differently from other inputs.
This reverts commit 9d48ca75.

That way Apps that have a long name (like OpenStreetGame for instance)
show their name troncated instead of continuing over the application frame.

(which breaks svg images for most browsers)

Also use OC_User::isLoggedIn to check if new authentication is needed for grouplist.php and userlist.php
For validateuser.php, credentials are always needed.