po:fixed error msgid and update the script of update_po

1.update "UEFI模式安装仅支持分区表为GPT的硬盘。如果执意安装,所有硬盘数据都将丢失。"
to "UEFI模式安装仅支持分区表为GPT的硬盘。如需安装请进入专家模式。"
The changed msgid is:
For installation, please enter the Expert Mode.
------TODO:林红霞 should update the zh_CN.po
2.'waring' -> 'Install Tips'

3.update the script of update_po:
    a.only updating pot instead of updating all po files
    b.add var app for the pot file name

4.installer.pot-->deepin-installer.pot

tower:https://tower.im/projects/17ce1bc3f1f14999931c914377f5af62/todos/e427415f608c404886f06d65b34b6200/#ff468342eb8a4b14b27485f46c121ea2
Change-Id: Ifb3d2d55cc241864b2fba00bbaa6a651e756fc44