Docs should highlight and recommend usage of wsgi

The README documentation should highlight the existence of the wsgi module and recommend its usage, rather than having this tucked away in a comment in the file:

- https://github.com/openstack/puppet-cinder/blob/master/manifests/wsgi/apache.pp#L16

"""
class { 'cinder::wsgi::apache':
  ssl => false,
}

class { 'cinder::api':
  service_name => 'httpd',
}
"""