In order to keep all three packages (zulip, zulip_bots,
zulip_botserver) in the same repo, all package files must now
be nested one level deeper.
For instance, python-zulip-api/zulip_bots/zulip_bots/bots/, instead
of python-zulip-api/zulip_bots/bots/.
tools/server_lib contains files copied as-is, or with minor
modifications, from the zulip/zulip repository when the api
code was split into this separate repository.
