Exponential backoff 


git-svn-id: https://gnunet.org/svn/gnunet@34228 140774ce-b5e7-0310-ab8b-a85725594a96
Reset the successor send time in notify confirmation message


git-svn-id: https://gnunet.org/svn/gnunet@34229 140774ce-b5e7-0310-ab8b-a85725594a96