Bug fix: Kimchi will try to create directory for 'DIR' storagepool

When you create a 'DIR' storagepool, kimchi does not check if the
path exists, returning errors when you try to activate the SP.
This path makes kimchi check the path and created the directory,
if it does not exist.

Signed-off-by: Rodrigo Trujillo <rodrigo.trujillo@linux.vnet.ibm.com>