Pool functions: ACLs and deletions now working.

Deleting a pool now just marks it as deleted in the DB.  This allows
users to continue to access files from jobs run in that pool, as
long as the scripts aren't deleted.

ACLs -- currently any user can set ACLs on their pools.  This might
not be desirable, as these pools will appear in ACL-permitted user's
pool lists, perhaps cluttering them up.

TODO: Admins who can set "public" pools, perhaps manage ACLs on
other's pools.