add statuses filter to GET /service/{}/job

can now pass in a query string `?statuses=x,y,z` to filter jobs based on
`Job.job_status`. Not passing in a status or passing in an empty string is
equivalent to selecting every filter type at once.

app/models.py

@@ -304,7 +304,14 @@ JOB_STATUS_FINISHED = 'finished'
 JOB_STATUS_SENDING_LIMITS_EXCEEDED = 'sending limits exceeded'
 JOB_STATUS_SCHEDULED = 'scheduled'
 JOB_STATUS_CANCELLED = 'cancelled'
-
+JOB_STATUS_TYPES = [
+    JOB_STATUS_PENDING,
+    JOB_STATUS_IN_PROGRESS,
+    JOB_STATUS_FINISHED,
+    JOB_STATUS_SENDING_LIMITS_EXCEEDED,
+    JOB_STATUS_SCHEDULED,
+    JOB_STATUS_CANCELLED
+]
 
 class JobStatus(db.Model):
     __tablename__ = 'job_status'