Support for postgres deferrable serializable transaction mode

[dspangen]

Postgres allows serializable transactions to declare that they are 'deferrable' (when also marked read-only), which allows a guarantee that the transaction will not fail with a serializability exception, and also provides better performance for such transactions. Read more here: http://www.postgresql.org/docs/9.2/static/sql-set-transaction.html

Any interest extending the gem to include this mode/ any guidance on where to include this functionality?