more generic template name

--HG--
rename : templates/CentOS-6.4-x86_64.ks.erb => templates/CentOS-6.x-x86_64.ks.erb
only do ntpdate if ntp server is defined
dhcp management moved to subclass
silly hack fixed
added automagic creation of hiera resources and fixed defaults
chenged defaults for purge params to be more failsafe