[multipathd]

[multipathd]

Jumbo patch :

o get rid of the last multipath configurator call
o introduce the native path group switching logic.
  For now only two behaviours :
  o FAILBACK_MANUAL
  o FAILBACK_IMMEDIATE
o get rid of path group ids unused bits
o paths and multipaths full scan is only done once now.
  Moved one step earlier, in child(). Lists housekeeping done
  through uevents (well, the mpvec part is yet to come)