Automated cherry pick of #643: Return err in Allocate if any error occurs #642: Add event when task is scheduled #638: Take init containers into account when getting pod resource #645: Order task by CreationTimestamp first, then by UID #647: In allocate, skip adding Job if its queue is not found #651: Return err in functions of session.go if any error occurs #652: Change run option SchedulePeriod's type to make it clear #655: Do graceful eviction using default policy #658: Address helm install error in tutorial.md #649: Preempt lowest priority task first #660: Fix sub exception in reclaim and preempt #666: Fix wrong caculation for deserved in proportion plugin #671: Change base image to alphine to reduce image size #673: Do not create PodGroup and Job for task whose scheduler is #685