'Returns list of instances on particular host.
If since is supplied, it will return the instances changed since that
datetime. since should be in ISO Format \'%Y-%m-%dT%H:%M:%SZ\''

@logged
def instance_get_all_by_host(self, hostname, since=None):

    search_opts = {'host': hostname, 'all_tenants': True}
    if since:
        search_opts['changes-since'] = since
    return self._with_flavor_and_image(self.nova_client.servers.list(detailed=True, search_opts=search_opts))
