Configure condor to join queue attached to cloud scheduler for csnodes

Add central_manager fact containing condor host connected to the
cloud scheduler that booted the VM.  Add grid secutrity directory to
contain certificates for condor.  TODO: retrieve certificates and
central_manager from metadata server and thus remove dependence on
context helper.

Changes:
   * new file:   condor/lib/facter/central_manager.rb
   * modified:   condor/templates/condor_config.local.csnode.erb
   * modified:   gce_node/manifests/grid_setup.pp