I found some arguments in yarn module take environment variables before system properties while the latter override the former in core module.

Author: WangTaoTheTonic <barneystinson@aliyun.com>
Author: WangTao <barneystinson@aliyun.com>

Closes #3557 from WangTaoTheTonic/SPARK4697 and squashes the following commits:

836b9ef [WangTaoTheTonic] fix type mismatch
e3e486a [WangTaoTheTonic] remove the comma
1262d57 [WangTaoTheTonic] handle spark.app.name and SPARK_YARN_APP_NAME in SparkSubmitArguments
bee9447 [WangTaoTheTonic] wrong brace
81833bb [WangTaoTheTonic] rebase
40934b4 [WangTaoTheTonic] just switch blocks
5f43f45 [WangTao] System property can override environment variable