https://issues.apache.org/jira/browse/SPARK-4990

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

Closes #3823 from WangTaoTheTonic/SPARK-4990 and squashes the following commits:

133c43e [WangTao] Update spark-submit2.cmd
b1ab402 [WangTao] Update spark-submit
4cc7f34 [WangTaoTheTonic] rebase
55300bc [WangTaoTheTonic] use export to make it global
d8d3cb7 [WangTaoTheTonic] remove blank line
07b9ebf [WangTaoTheTonic] check SPARK_CONF_DIR instead of checking properties file
c5a85eb [WangTaoTheTonic] to find default properties file, search SPARK_CONF_DIR first