status page: Add confirmation dialog page for "reboot"
and "Power off" buttons

Previously the status page missed confirmation dialog page
for "reboot" and " Power off" buttons.
Now this confirmation page has been added.

Change-Id: I56063e812d898e7e7d5490b15e5845115fe45be0
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=968886
Signed-off-by: hadong <hadong0720@gmail.com>