* Add parameter 'instance_communication_parameter' to the Python
  'ganeti.objects.Cluster' and the Haskell 'Ganeti.Objects.Cluster'.

* Update Haskell 'QueryClusterInfo' to return also the
  'instance_communication_network' parameter.

* Update Python 'LUClusterQuery' to return also the
  'instance_communication_network' parameter.

* Update Python 'ShowClusterConfig' to include information about the
  'instance_commuication_network' parameter

* Update 'ganeti.objects.Cluster.UpgradeConfig' to ugprade also
  'instance_communication_network' parameter to the empty string, if
  unspecified.

* Update the configuration upgrade tool (i.e., 'tools/cfgupgrade') to
  handle upgrading of the 'instance_communication_network' parameter
  as well as downgrading.

Signed-off-by: Jose A. Lopes <jabolopes@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>