Fix NumberFormatException for create_file_by_policy; fix NullPointer for filterTableFiles; fix version check bug inf create_file_by_policy.
modify alter dbproperties change null to not null
modify alterFileSplit but not successfully
Bug fixing commit: reopen, checker thread, listDevice ...
alter filesplitby
Merge remote-tracking branch 'origin/v0.2' into zhuqihan
alter create view sucessfully