Accept more word delimiters when updating hooks

When updating container names in hook files during a container clone,
we substitute the new container name for the old any time the old name
shows up as a separate word.  This patch adds the four characters
'.,_-' as additional delimiters.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
api_clone: don't remove storage if we haven't created it

In the best case we'll get errors about failing to remove it.  In the
worst case we'll be trying to delete the original container's rootfs.

Reported-by: zoolook <nbensa+lxcusers@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>