Also create seperate account security options page

This commit requires a new database table

This was an automatic mass-replace. Manual replacement of array(...)
will continue

- Default interval now 30 seconds (breaking!)
- Don't add default parameters to QR code (smaller)

Fixes #22

2FA class stolen from RobThree and stripped down.
Works best with qrencode utility installed, but will fall back to using
google charts if qrencode is missing.