'Get a list of extensions.
The listing result is an object with property "items". Each item is
an extension.
Example GET:
http://localhost/api/cinder/extensions'

@rest_utils.ajax()
def get(self, request):

    result = api.cinder.list_extensions(request)
    return {'items': [{'alias': e.alias, 'description': e.description, 'links': e.links, 'name': e.name, 'namespace': e.namespace, 'updated': e.updated} for e in result]}
