Translatable country names (Solves #137)

[bidaian]

This pull requests adds the country codes and English names to openwapp.en-US.properties and it adds a l10n lookup in scripts/collections/countries.js (just one line), based on the country code.

For those locales not translating the country names, nothing changes. But I can prepare another pull request with the translations, from the same source (Firefox - release channel).

I don't know how to test the lookup inside countries.js, and since I'm working on my actual primary devices, I cannot uninstall and reinstall from scratch. Could you take a look at it?

[Timmaks]

This is not working, The country list is empty if you did not active your sim with the simcode and if you did active the sim the line 'You have a {{country}} phone number. Change it if it is not correct' does not show a countryname at the place of {{country}}

[willyaranda]

Mmmm… I don't know if I like this. It's a huge piece of strings to be translated. Also, we need to see if they are listed by the code or the translated name. For example, "Spain" in spanish is "España", and "Germany" is "Alemania". We need to see if we want a sort by code or name.

Both options have problems, for example:

+am=    Armenia
+an=    Netherlands Antilles

[Timmaks]

@bidaian did you work on this?