TODO
====

-   Complete i18n.

-   Automaticaly add a number of invites for new members. 
    (And modify the configlet to enable modification of number of 
    invites to give new users.

-   Re-add expiration functionality (invitation expires after configurable time
    period).

-   Modify configlet to enable modification of invitiations e-mail "Sender" in
    Plone. 

-   In the configlet, don't show "Number of days the invitation stays active"
    if there are no members.

-   Do not lose invitations when re-installing.

-   See if we can subclass zope.interface.Interface instead of
    IDefaultPloneLayer (interfaces.IPloneInvitePolicy)
