create new cidr type for data storage

it turns out that the 149 migration was overly agressive in its
IPAddress conversion, as we actually have a few columns that are
really CIDR values. This means that 39 chars isn't enough space to
store even a normalized IPv6 cidr in the worst case (you need 4
more to support /127).

We must also normalize IPv6 address cidrs otherwise 43 chars isn't
long enough. This was more of a problem in theory, than in practice,
as real IPv6 addresses rarely are non compressible.

This adds a migration to bump up the CIDR columns to 43 characters.
There is an infinitessimal chance that someone using mysql and long
IPv6 values might loose data in 149 because of truncation. This
doesn't address that, which would require modifying 149.

The native pg CIDR column type is not used because it would require
additional scrubbing of the data as CIDR is invalid if any host bits
are set (and it will fail on type conversion).

Fixes bug #1127696

Change-Id: I54539ac9c257d726bc4db5943169b5284cc847d3
Merge "create new cidr type for data storage"