Adds priority for aurora-scheduler (#13)

Adds priority for task config

task.go

@@ -78,7 +78,8 @@ func TaskFromThrift(config *aurora.TaskConfig) *AuroraTask {
 		Role(config.Job.Role).
 		Name(config.Job.Name).
 		MaxFailure(config.MaxTaskFailures).
-		IsService(config.IsService)
+		IsService(config.IsService).
+		Priority(config.Priority)
 
 	if config.Tier != nil {
 		newTask.Tier(*config.Tier)
@@ -287,6 +288,12 @@ func (t *AuroraTask) IsService(isService bool) *AuroraTask {
 	return t
 }
 
+//set priority for preemption or priority-queueing
+func (t *AuroraTask) Priority(priority int32) *AuroraTask {
+	t.task.Priority = priority
+	return t
+}
+
 // Add a list of URIs with the same extract and cache configuration. Scheduler must have
 // --enable_mesos_fetcher flag enabled. Currently there is no duplicate detection.
 func (t *AuroraTask) AddURIs(extract bool, cache bool, values ...string) *AuroraTask {