Localization support and other small modifications.

I saw this https://github.com/corenominal/cb-welcome/pull/7 pull request and decided to add localization support. So, here it is!
There are two possible problems that I know of:
`fold` does not treat unicode characters correctly.
Bash `${var^^}` expansion does not work for other characters besides english A-Z

But this is a great start. Most probably German translation will work fine.
I'll fix these problems if someone decides to make a real translation.