add support for user settings

Basic setting pages that allow users to edit easily their LDAP attributes
via web forms.

Settings:
* Profile settings (first name , last name, email , timezone, birthday,
* passwords)
* Contact settings (website, IM , GPG fingerprint, location,
longitude, latitude)
* Gentoo settings (mentors, developer bug, join date, retire date,
ssh key)
Notes:
* Currently settings work only with single values and not
* listfields.
* Timezone needed for OpenID (cc: @mgorny)
* Gentoo Account Settings page is available for everyone.(testing
purposes)