How to add a new language to our app translations

This outlines how to introduce a new language to our translation system.

1. Set up the desired language in the admin backend. This is a good starting point to find correct values for the language code and plural forms.
2. Request a \o/ dev to create a properly named duplicate for each of the original messages.properties file locally on the pootle server. For example, if the newly created languages code would be xyz the filename should be messages_xyz.properties.*
3. Add the newly set up language to each project (e.g. Cloud and Core) by navigating to that projects page and opening the 'Administrate' tab. After saving  and navigating to the to projects page there should be a bit of loading time leading to the new language being added.

*Once we figure out how to change the way Pootle names automatically generated new files, this step would no longer be necessary. (Temporarily fixed, details here)