Add gerrit owner information to status.json

gerrit.query does return the owner information, we can save that
in the Change object and serialize it to status.json

Change-Id: Ib505ef8703bc60058d2775f522fcc3d02910b05f
diff --git a/zuul/model.py b/zuul/model.py
index b03bbb0..67ce8be 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -709,6 +709,10 @@
         ret['project'] = changeish.project.name
         ret['enqueue_time'] = int(self.enqueue_time * 1000)
         ret['jobs'] = []
+        if hasattr(changeish, 'owner'):
+            ret['owner'] = changeish.owner
+        else:
+            ret['owner'] = None
         max_remaining = 0
         for job in self.pipeline.getJobs(changeish):
             now = time.time()
@@ -857,6 +861,7 @@
         self.approvals = []
         self.open = None
         self.status = None
+        self.owner = None
 
     def _id(self):
         return '%s,%s' % (self.number, self.patchset)
diff --git a/zuul/trigger/gerrit.py b/zuul/trigger/gerrit.py
index 6966488..bf591c4 100644
--- a/zuul/trigger/gerrit.py
+++ b/zuul/trigger/gerrit.py
@@ -371,6 +371,7 @@
         change.approvals = data['currentPatchSet'].get('approvals', [])
         change.open = data['open']
         change.status = data['status']
+        change.owner = data['owner']
 
         if change.is_merged:
             # This change is merged, so we don't need to look any further