Update postgres adapter column definition with cast_type
In Rails 4.2, support for Jsonb datatype was added for postgres

Commit - https://github.com/rails/rails/commit/99b82fdf03fcf6d6ca8e2d810ba35011723a5267
Add support for XML as present in Rails 4.2 for PG

- This was done to not rely on sql_type for quoting xml values.
Commit - https://github.com/rails/rails/commit/f6968bd601e38fb5060c7bc577331f97ed5e232c
Use the generic type map for all PG type registrations

Commit - https://github.com/rails/rails/commit/4826a4ab348e59c3ac1f6c31fd73f93eabb91a3b
Type is changed from Rails 4.2
PG type map initialization was extracted to TypeMapInitializer in Rails 4.2

Commit - https://github.com/rails/rails/commit/15285f22483363d2fee8b501a1f2a39de03d7473