PortageVersion: show bad version string in exception

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

lib/puppet/property/portage_version.rb

@@ -7,7 +7,7 @@ class Puppet::Property::PortageVersion < Puppet::Property
 
   validate do |value|
     unless Puppet::Util::Portage.valid_version? value
-      raise ArgumentError, "#{name} must be a properly formatted version"
+      raise ArgumentError, "'#{value}' must be a properly formatted version"
     end
   end
 end