Camo is a caching image proxy, used in Zulip to avoid mixed-content
warnings by proxying HTTP image content over HTTPS. We've been using
it in zulip.com production for years; this change makes it available
in standalone Zulip deployments.
With this change, we are now testing the production static asset
pipeline and installation process in a new testing job (and also run
the frontend/backend tests separately).
This means that changes that break the Zulip static asset pipeline or
production installation process are more likely to fail tests. The
testing is imperfect in that it does not have proper isolation -- we
build a complete Zulip development environment and then install a
Zulip production environment on top of it, so e.g. any apt
dependencies installed for Zulip development will still be available
for the Zulip production environment. But, it's better than nothing!
A good v2 of this would be to have the production setup process just
install the minimum stuff needed to run `build-release-tarball` and
then uninstall it / clean it up so that we can do a more clear
production installation, but that's more work.
While the docu on https://www.zulip.org/server.html says:
```
cd /root/zulip
./scripts/setup/install
```
This script downloads the `python-django-guardian_1.3-1~zulip4_all.deb` file to current working dir (`/root/zulip` if you follow the docu), but tries to install it from /root/.
This fails obviously. So i changed the download location to /tmp/.
We don't use apache in the main app -- only for the SSO situation --
this code was just copied from our own install script. And it caused
problems at CUSTOMER13 because they installed Apache in preparation for
the SSO integration, but restarting it failed.
(imported from commit 3f2961574134847c836e8b69736f60d9f8790201)