Downgrade database.

def downgrade():
    """Downgrade database."""
    # Remove 'created' and 'updated' columns
    op.drop_column('oauthclient_remoteaccount', 'created')
    op.drop_column('oauthclient_remoteaccount', 'updated')

    op.drop_column('oauthclient_remotetoken', 'created')
    op.drop_column('oauthclient_remotetoken', 'updated')

    op.drop_column('oauthclient_useridentity', 'created')
    op.drop_column('oauthclient_useridentity', 'updated')