audit: Add IP ACL functions

Add some functions to allow the use of IP Access Control Lists to
allow users to lock down access to the application.

This works for both IPv5 and IPv6 address/networks e.g a user could
specify the following to only allow access from

    192.168.1.10
    2a01:7e00::/64

Signed-off-by: Andrew Clayton <andrew@digital-domain.net>
db: Add schemas for the passwd, ipacl & utmp tables

Signed-off-by: Andrew Clayton <andrew@digital-domain.net>