修改作业优先级

change_job_priority

改变作业的优先级，作业状态为Stopped时才能改变作业的优先级。

参数说明：

属性	类型	描述
job	CreateResponse, str	作业标识符
priority	int	作业优先级，[0-1000]，数值越高优先级越高

返回值说明：

change_job_priority方法将返回一个 ActionResponse 对象, ActionResponse仅提供了request ID和状态码两个属性。

e.g.

try:
    client = Client(...
    ...
    # Job created before.
    job_id = "job-xxxx"
    # Only the priority of stopped jobs can be changed.
    client.stop_job(job_id)
    assert client.get_job(job_id).State == 'Stopped'
    # Try to change priority.
    client.change_job_priority(job_id, 99)
    client.start_job(job_id)
    assert client.get_job_description(job_id).Priority == 99
except ClientError, e:
    print(e)