Fix start failed job not working

Currently, when we start a failed job, nothing will happen.
It is because freezer-scheduler has filtered all the job with
status 'completed'. This patch will fix it.

Change-Id: I9ef420ba5dbf1e80582a6b0ab947646630a6b7fa
Closes-Bug: #1625189

freezer_api/api/v1/jobs.py

@@ -258,6 +258,8 @@ class Job(object):
     def start(self, params=None):
         if self.job_schedule.get('event') != 'start':
             self.job_schedule['event'] = 'start'
+            self.job_schedule['status'] = ''
+            self.job_schedule['result'] = ''
             self.need_update = True
             return 'success'
         return 'start already requested'

freezer_api/api/v2/jobs.py

@@ -271,6 +271,8 @@ class Job(object):
     def start(self, params=None):
         if self.job_schedule.get('event') != 'start':
             self.job_schedule['event'] = 'start'
+            self.job_schedule['status'] = ''
+            self.job_schedule['result'] = ''
             self.need_update = True
             return 'success'
         return 'start already requested'

freezer_api/common/json_schemas.py

@@ -72,7 +72,7 @@ schedule_properties = {
     "status": {
         "id": "status",
         "type": "string",
-        "enum": ["completed", "stop", "scheduled",
+        "enum": ["", "completed", "stop", "scheduled",
                  "running", "aborting", "removed"]
     },
     "result": {