Currently it's very easy for contact details to get out of sync, the
simplest example is:
A & B are contacts.
A changes name.
B receives the updated name.
B re-install the app.
Until A changes name again, B will not see their name, picture and won't
be able to send push notifications.
This PR changes the behavior to publish account informations to contacts
every 24 hrs, to add some redundancy in this cases.
It also publishes a contact code every 12hrs.
Signed-off-by: Andrea Maria Piana <andrea.maria.piana@gmail.com>