Postgres 9.4 Jsonb support

This patchset adds support for jsonb in the forthcoming Postgresql 9.4 release (currently in beta).

It correctly marshals the json data to and from the database, as well as adding support for the ? (has_key) and @> (contains) operators.

Tests are included and passing.
Hi Mike, no - they aren't supported by the traditional 'json' format, only in jsonb.  See http://www.postgresql.org/docs/9.4/static/functions-json.html#FUNCTIONS-JSONB-OP-TABLE for reference.