Import a compatibly-named postgresql dialect module
Import a compatibly-named postgresql dialect module

Author: Phillip Cloud <cpcloud@fb.com>

Closes #823 from cpcloud/sqlalchemy-compat and squashes the following commits:

7a1656d [Phillip Cloud] Import a compatibly-named postgresql dialect module

wesm/ibis,cloudera/ibis,ibis-project/ibis,ibis-project/ibis,cloudera/ibis,ibis-project/ibis,cpcloud/ibis,deepfield/ibis,deepfield/ibis,cpcloud/ibis,wesm/ibis,cloudera/ibis,ibis-project/ibis,wesm/ibis,deepfield/ibis,cpcloud/ibis,cpcloud/ibis,deepfield/ibis