Given a sequence of endpoints obtained via name resolution, start connecting to a new one every self._attemptDelay seconds until one of the connections succeeds, all of them fail, or the attempt is cancelled.
| Parameters | endpoints | a list of all the endpoints we might try to connect to, as determined by name resolution. (type: list of IStreamServerEndpoint) |
| Returns | a Deferred that fires with the result of the endpoint.connect method that completes the fastest, or fails with the first connection error it encountered if none of them succeed. (type: Deferred failing with error.ConnectingCancelledError or firing with IProtocol) |