try to use new policy in upgrade action
update backend for new signal
Update zh_TW.po

并 --> 並
Update zh_HK.po

并 --> 並
change upgrading page with new policy
finish upgrade cancel and hide window
Merge branch 'patch-2' of github.com:lihongwu/deepin-software-center-private into lihongwu-patch-3
Merge branch 'lihongwu-patch-3' into develop