Fix tests for sqlalchemy utils
Fix tests for sqlalchemy utils

This fix tests to be able to run it with postgresql and mysql.

Some tests should be run only on sqlite

Method create_shadow_tables raises different exception in different
backends (when we try to create duplicate table):
In postgresql it is ProgrammingError
In sqlite and mysql it is OperationalError
So create new Exception that will be raised in both cases.

bp db-common-migration-and-utils

Change-Id: I11be23106bc01bd3c72dad30edfb31a17177bb34

n0ano/ganttclient