feat(halyard): Added halyard to list of built artifacts (#1464)

* feat(halyard): Added halyard to list of built artifacts

What I came to realize was that if halyard is published to the same bintray repo as Netflix's Spinnaker releases, it'll overrwrite the spinnaker source list with our private build repo, making it impossible to update halyard.

* Update build_release.py

dev/build_release.py

@@ -65,7 +65,7 @@
 
 SUBSYSTEM_LIST = ['clouddriver', 'orca', 'front50',
                   'echo', 'rosco', 'gate', 'igor', 'fiat', 'deck', 'spinnaker']
-ADDITIONAL_SUBSYSTEMS = ['spinnaker-monitoring']
+ADDITIONAL_SUBSYSTEMS = ['spinnaker-monitoring', 'halyard']
 
 def ensure_gcs_bucket(name, project=''):
   """Ensure that the desired GCS bucket exists, creating it if needed.