interactions: add methods to update interaction status

If a message is outgoing, update the status from daemon's signals. If a
message is incoming, the client have the ability to change the status of
the interaction from UNREAD to READ.

Change-Id: If47fed5e1a2ecbdd52745e150fc08146ca7a6cbd
Reviewed-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>