[wrt][xwalk-2943]Update tests with pyunit for packertool

Impacted TCs num(approved): New 0, Update 262, Delete 0
Unit test Platform: Android
Android test result summary: Pass 262, Fail 0, Block 0
Merge pull request #1361 from wanghongjuan/wrt/packertool-improve-script

[wrt][xwalk-2943]Update tests with pyunit for packertool