Serialize postgres arrays correctly in AR update methods. Fixes #12261

As described in #12261 the column information was not being passed in for sanitization methods, therefore db-adaptor-specific quoting could not trigger resulting in an exception => https://gist.github.com/senny/6725398.

The new version of `quote_bound_value` now explicitly checks for array type columns, which is not flexible (I have a feeling the same problem might apply to other postgres-specific types), so it might need refactoring, suggestions welcome.

Thanks @senny for your help!