Add configurable timeout to ET requests.

@jgmize I think this will help too. Should keep basket from churning forever.
I'd still like to check into catching this particular timeout and catching it
with statsd or something.
Right, but Client.options aren't being passed during the [HttpAuthenticated instantiation](https://github.com/mozilla/basket-lib/blob/master/packages/suds/suds/client.py#L107); they are separate dicts.