Upgrade database.

def upgrade():
    """Upgrade database."""
    current_date = datetime.utcnow()

    # Add 'created' and 'updated' columns to RemoteAccount
    _add_created_updated_columns('oauthclient_remoteaccount', current_date)

    # Add 'created' and 'updated' columns to RemoteToken
    _add_created_updated_columns('oauthclient_remotetoken', current_date)

    # Add 'created' and 'updated' columns to UserIdentity
    _add_created_updated_columns('oauthclient_useridentity', current_date)