Next vz id will consider vz directories as well

The next vz id to use to create a new container should also consider
the vz id directories that exist in addition to containers that are
running. There can be container that was deleted but for some reason
did not clean up all its directories within /var/lib/vz/{private,root}
which will cause the next container that reuses that id to fail.

Change-Id: I5813c30f594d99a6a21054cd5b3caa24d85039fe
Delete host device during deataching of volume

The host device (/dev/*) should be removed after the device is removed
from within the container, else a kernel I/O error will occur.

Change-Id: I43ae839d6a9c8643a43b0c063f39715c53552c77
Merge "Next vz id will consider vz directories as well"
Fix container.get_next_id bug

Change-Id: Ia7238667b05fd6f969fc087af0f82dea38a3932d
The get_next_id must be string to avoid breaking existing code

The cast as string was left out of the recent patch. Adding it again.

Change-Id: I13ca9432b9ae892886e07ad669274ff4186dfba4