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/.
Update integration to use the latest Google API client.
Move Google Account authorization code to a separate file.
Move relevant files from 'bots/' to 'api/integrations/google/'.
Add documentation for integration.