Updated strings.xml and .txt files with pt-BR translations

Portuguese translations! :smile: 

I'll review it tomorrow, but I think that everything is correct. The word "tile" in Brazil is more related with roof tiles, so I'm translating it as "bloco" (block), to make more sense in the context of the game. "Sign in" here in Brazil is more called "Logar" (to login), so it's not the literal translation but it's just for make sense here.

But let me know if you need more help with pt-BR translations, I'll be glad to help!
@alexjlockwood I can also change some word choices to make it smaller, what you think?