Use the inet data type for supermasters.ip on postgrsql.

Use pgsql’s inet data type for v4 and v6 IP addresses in the
supermasters table.

The guarantees that the address will fit, that the queries will
return the addresses in canonical format, and correctness in that
nothing other than an IP address can be stored in that column.

Signed-off-by: James Cloos <cloos@jhcloos.com>