Update root_helper for Debian
Update root_helper for Debian

This commit updates the root_helper used for Debian
systems. The packaging for Ubuntu Precise has been
updated to include nova-rootwrap.

This commit updates the params class to specify nova-rootwrap
as the default root_helper for Debian.

TelekomCloud/puppet-nova,nhinds/puppet-nova,apenney/puppet-nova,larsks/puppet-nova,bodepd/puppet-nova,JioCloud/puppet-nova,bodepd/puppet-nova,aquto/puppet-nova,pllopis/puppet-nova,ody/puppet-nova,stratustech/puppet-nova,nhinds/puppet-nova,dprince/puppet-nova,DarkHorseComics/puppet-nova,esteve/puppet-nova,aquto/puppet-nova,varunarya10/puppet-nova,varunarya10/puppet-nova,JioCloud/puppet-nova,balle/puppet-nova,ody/puppet-nova,mgagne/puppet-nova,datacentred/puppet-nova,aimonb/puppet-nova,madkiss/puppet-nova,arnaudmorinol/puppet-nova,esteve/puppet-nova,cristifalcas/puppet-nova,balle/puppet-nova,datacentred/puppet-nova,aimonb/puppet-nova,javiplx/puppet-nova,DylanYu/puppet-nova,gwdg/puppet-nova,stratustech/puppet-nova,aimonb/puppet-nova,mgagne/puppet-nova,gwdg/puppet-nova,dprince/puppet-nova,mgagne/puppet-nova,apenney/puppet-nova