storefront internationalization

[erosson]

I created the android English storefront by copying and modifying quirk's ios storefront. Repeat that for other languages too, and s/quirk/freecbt/

I added a blurb about freecbt forking quirk to the english version - not really practical to do that for other languages sadly, but that shouldn't block this

might be a good idea to put storefront text into git, so any future forks don't have to hunt for it

[erosson]

quirk translation archaeology: ios storefront links, pull request links by language, keywords and storefront translation text when available

https://docs.google.com/spreadsheets/d/1n9OCZsJQGms-iuNOMEvnZP2ankb2-zWObszSAnYU6JE/edit?usp=sharing

• a pull request with keywords and storefront text was ideal - but older languages often didn't translate this, so have untranslated storefronts
• the ios storefront doesn't seem to have a way to view its keywords; langs with storefront text but no keywords are from there. assuming flaque is too busy to look them up, can we find an api or something for these?
• I can see that for some languages (hindi!) s/quirk/freecbt/ will be nontrivial
• there's a few contributed translations that never got merged into quirk. I think I can legally use them (is the pull request automatically gpl-licensed if it wasn't merged? I think so...?), but I will obviously attempt to notify the contributors first
• we have to put storefront text/keywords in source control, what a mess (but to be fair, I would've made the same mistake if I'd started this app!)

[erosson]

we have to put storefront text/keywords in source control

fastlane looks like the way to do this, and we may also want fastlane for #16 anyway

Looks like the quirk folks tried to use fastlane but abandoned it, or didn't use it for metadata? there's no ios app store metadata at all, anyway. I'll start using it for storefront data, but not for deployments just yet.

added fastlane docs to CONTRIBUTING.md