Periodic tasks

• unconfirmed signature a week or max 2 weeks ago? send a reminder to confirm
• unconfirmed user a week or max 2 weeks ago? send a reminder to confirm
• unconfirmed signature and petition closes next week? send a reminder to confirm, the "last call" unless petitions:updated_at is less than a week ago (to prevent petitioners from prolonging petition with a week to provoke last call reminders or annoying those who did not want to confirm even more)
• unconfirmed signature for a petition closed one month ago? delete signature
• petition is closed at due date, then announcement to recipient of petition with request for an answer and a reference number, 'progress' value updated
• announcement unanswered for two weeks, repeat the request for an answer.
• procedure start date reached, but no