Add access to raw host in ipaddr module.

An issue in rails (activerecord) showed up which indicates that there
are at least some IPAddresses which continue to use the unmasked piece
of the address.

https://github.com/rails/rails/issues/14857

This is apparently the difference between the "cidr" data type and the
"inet" datatype. This change exposes an api so that the correct address
type can be used.