Murano migrations failed due to mysql driver was updated in devstack

The problem is more complicated, that we expected

We do support SQLite migrations. that why we do have this function to support 'alter' in sqlite:

https://github.com/openstack/murano/blob/master/murano/db/migration/alembic_migrations/versions/004_change_package_desc_type.py#L39

After switching to pymysql, force ignoring of foreign keys in Mysql is not working, so it's not possible to drop the table in transform_table functions.

We can drop sqlite support and use alter in this migration.

Fix proposed to branch: master
Review: https://review.openstack.org/190870

Reviewed: https://review.openstack.org/190870
Committed: https://git.openstack.org/cgit/openstack/murano/commit/?id=508739984da3740d8d2fe1acb84ebce88688c7f1
Submitter: Jenkins
Branch: master

commit 508739984da3740d8d2fe1acb84ebce88688c7f1
Author: Kirill Zaitsev <email address hidden>
Date: Fri Jun 12 02:51:16 2015 +0300

    Migrations: ignore mysql fk cheks for any mysql driver

    Before mysql migrations disabled foreign key checks only for
    mysql+mysqldb engine. Currently mysql+pymysql is preferred engine. This
    change disables FK checks for any mysql engine available.

    Change-Id: I536480559260c4be11b6e615c0df8f012798be9d
    Closes-Bug: #1464271