Reloading volumes from config file was broken

Reloading volumes from config file was broken

load_volumes() is supposed to be a "reenetrant" function called from
various places in different programs (afpd, cnid_metad) to reload the
config for updating the volume list.

Fix the loop freeing volumes that are deleted.

Simplify the loop checking for paths and volume names in createvol().
This is also the loop which checks if a volume is already loaded
when config has been loaded before.

Remove checks for nested paths.

Fixes bug #474.