Apply subtype repr logic to JSON/JSONB

Apply subtype repr logic to JSON/JSONB

Fixed bug where Postgresql JSON/JSONB types rendered on SQLAlchemy
1.1 would render the "astext_type" argument which defaults to
the ``Text()`` type without the module prefix, similarly to the
issue with ARRAY fixed in :ticket:`85`.

Also modifies the ARRAY approach from :ticket:`85` to be
regular expression based for safer targeting of the inner
repr() type.

Change-Id: I66d51301f4bf5b747b5e8da26a83cbff075d71b2
Fixes: #411