This is a preparatory commit for using isort for sorting all of our
imports, merging changes to files where we can easily review the
changes as something we're happy with.
These are also files with relatively little active development, which
means we don't expect much merge conflict risk from these changes.
This adds a new API for sending basic analytics data (number of users,
number of messages sent) from a Zulip server to the Zulip Cloud
central analytics database, which will make it possible for servers to
elect to have their usage numbers counted in published stats on the
size of the Zulip ecosystem.
Tim Abbott