Backend improvements

[erral]

Some backend improvements:

• Why are we creating the docker image with a specific requirements-docker.txt file instead of the requirements.txt file? I think that that makes everything more complex. I was hit by this, and I just did not understand what's going on: I added some dependencies to requirements.txt on development, build the docker image, deploy it, and my dependencies were missing. Why not use the same file to build the docker image? That's what I do in the PR.
• Running the update_locale script installed in the virtualenv is wrong. What if several packages install the same script? Which one wins? Nobody knows! I was hit by this too: I had a package installed as a dependency (collective.contentrules.telegram), which is a package generated with bobtemplates.plone boilerplate which also installs the update_locale script in bin (btw, the backend_addon also does this), so when running make i18n in my backend add-on, the installed one was executed, and in my case the collective.contentrules.telegram one was executed. I guess that when running make i18n in our backend folder, we want to update our own package's locales! That's what this PR does, calling update.sh in this very add-on.

[davisagli]

Makes sense to me.

[ericof]

About the requirements-docker.txt, ok.
But the update_locale I would go on a different route. (There is an issue about this opened here)

[erral]

I will open a PR removing the requirements-docker.txt

I talked to Érico and he has some ideas about the update_locales scripts, so I will leave that out of the PR.

[davisagli]

Sounds like we should close this one then.