This script in `zulip_ops` is handy for managing EC2 instances. It uses
`boto`, which isn't available in `trusty` for Python 3. The use of
`boto` here isn't particularly deep, so we could replace it with some
more manual HTTP calls if it comes to that. For now, just mark it to
stay on Python 2 while we move the app and all the rest of the ops code
(except this and another straggler or two) to Python 3.
Also make a comment on this package in the Puppet manifest clearer
about what it specifically refers to.