[SPARK-5002][SQL] Using ascending by default when not specify order in order by

spark sql does not support ```SELECT a, b FROM testData2 ORDER BY a desc, b```.

Author: wangfei <wangfei1@huawei.com>

Closes #3838 from scwf/orderby and squashes the following commits:

114b64a [wangfei] remove nouse methods
48145d3 [wangfei] fix order, using asc by default