Add UUID format for ULID

[budarin]

In databases, the UUID has size advantages in the internal representation compared to the string representation

https://www.postgresql.org/docs/9.1/datatype-uuid.html
https://dba.stackexchange.com/questions/89429/would-index-lookup-be-noticeably-faster-with-char-vs-varchar-when-all-values-are/89433#89433

[aarondcohen]

The uuid type is already supported for db reads and writes. id.toRaw() converts the id to hex, which is compliant with one of the uuid standard formats. Use Ulid.fromRaw for the reads. There might be a bug on the reads where we need to strip - before the conversion.