Hard reboot doesn't re-create instance folder

When use share storage like ceph, instance's disk data is in ceph,
instance's disk doesn't rely on local instance folder anymore. So
when rebooting a instance, we should create the instance folder if
it is missed.

Closes-Bug: #1349978

Change-Id: I5948c7979a7dbe7764fba6cad1d9867893824024
Merge "Hard reboot doesn't re-create instance folder"