Propagate better authentication boilerplate across services

I just copy-pasted @jamiehannaford's better version from #352 into all of the other services. This'll do until we get to that backlog item that @rdodev mentions.

Also there was apparently a ton of trailing whitespace in the `index.rst` files. Er, sorry about that.
Does it feel weird at all that we have a non-SDK in the group (`curl`)?