Convert `launch_server` to use the new request function

There's [`IsBoundWith`](https://github.com/rackerlabs/otter/blob/master/otter/test/utils.py#L73), is a matcher that can be used with [`mock_log`](https://github.com/rackerlabs/otter/blob/master/otter/test/utils.py#L255)

See:  https://github.com/rackerlabs/otter/blob/master/otter/test/test_supervisor.py#L788