Teach kano-updater to migrate Kanux repository

 * Defined new transition migrations from 1.1 and 1.2 to 1.3
   where Kanux repo will be changed with a sed command

 * I am pretty sure I am missing some actions on this module,
   can't see where the preupdate scenarious are being called from,
   but pychecker seems to be happy, extracted code works ok.