Add schema support for Postgresql
I ran w/some of your ideas and have added functionality for switching search path and specifying schema when introspecting:

bc465f467d0f3ccbf03c1b49ea2b2ecb04c0c765
963cfe41c9af773be934e36fb5e3a17eaeb85ff6
 Cool.
I'll continue learning peewee.
Cheers,
Paul.

Hi,

I've been playing a bit with peewee and had to add a few things to inspect a Postgresql database within a schema.
I haven't done much testing apart from this local Postgresql (a MusicBrainz DB mirror).

Any thoughts?

Cheers.
Paul.
