Simple-streams fail when use_swift false

[Michał Ajduk]

Simple streams charm has a hardcoded sync path:

            if not charm_conf['use_swift']:
                # Sync output directory to APACHE_DATA_DIR
                subprocess.check_call([
                    'rsync', '-avz',
                    os.path.join(tmpdir, charm_conf['region'], 'streams'),
                    APACHE_DATA_DIR
                ])

This code fails when the unit is not collocated with apache and does not use swift.