Add `remember me` backup code
Cf https://github.com/FreederTeam/Freeder/issues/25#issuecomment-53045688

This updates need a clean reinstall of Freeder as it updates the
database structure.

Another easy way to avoid reinstalling it is to run:

* `sqlite3 data/db.sqlite`
* `ALTER TABLE users ADD remember_token TEXT;`
DO NOT let the template have access to hashed user password
MAJOR In anonymous view, `Logout` link is still present, instead of a `Login` link.

See https://github.com/FreederTeam/Freeder/issues/25#issuecomment-53045688.
Stick button

See
https://github.com/FreederTeam/Freeder/issues/25#issuecomment-53045688
Merge master