fix missing variable declaration

Author: Tim Meusel

manifests/master.pp

@@ -46,6 +46,8 @@
 # ['serialization_format']      - defaults to undef, otherwise it sets the preferred_serialization_format param (currently only msgpack is supported)
 # ['strict_variables']          - Makes the parser raise errors when referencing unknown variables
 # ['always_cache_features']     - if false (default), always try to load a feature even if a previous load failed
+# ['serialization_format']      - defaults to undef, otherwise it sets the preferred_serialization_format param (currently only msgpack is supported)
+# ['serialization_package']     - defaults to undef, you can specify a package name that provides ['serialization_format']. If undef, a gem will be used named like ['serialization_format']
 #
 # Requires:
 #
@@ -113,6 +115,7 @@
   $upstream                   = $::puppet::params::upstream,
   $backend_process_number     = $::puppet::params::backend_process_number,
   $serialization_format       = undef,
+  $serialization_package      = undef,
   $always_cache_features      = false,
 ) inherits puppet::params {