db: mysqldb: Fix the UnboundLocalError

The code out of try/except peer will not be treated as part of the
block. Thus the return here didn't work with the function but ran
as a single command. 'res' was not a global variable, so the
reture would cause a UnboundLocalError.

Signed-off-by: GuofengLiu <lgf612@sina.com>
data: add arguments for two methods

Add 'field' argument for both lowestByDate() and highestByDate()
 to extend usability.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>
strategy:turtle: sync in home

Sync turtle in home.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>
test: update tests for turtle and turt1

Change because of the code implement in turtle and turt1.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>
Merge branch 'winf-dev' into zhengwang-dev