Set default storage pool to autostart and make persistent

The default storage pool wasn't set to autostart, and wasn't
persistent. If a user wants to continue to use any VMs they
have created in kimchi (maybe only for troubleshooting) but
kimchi isn't active, the default pool may not be active.

Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>