Only setup ppas when osfamily is Debian

examples/site.pp

@@ -4,6 +4,7 @@
 
 Exec { logoutput => 'on_failure' }
 
+if($::osfamily == 'Debian') {
   stage { 'keystone_ppa':
     before => Stage['main'],
   }
@@ -14,6 +15,7 @@ class { 'apt':
   class { 'keystone::repo::trunk':
     stage => 'keystone_ppa',
   }
+}
 
 # example of how to build a single node
 # keystone instance backed by sqlite