Add portuguese translation

[franciscoBSalgueiro]

No description provided.

[GyulyVGC]

A PR for Brazilian Portuguese has also been opened (#136).
Is it meaningful in your opinion to have both languages featured or you guys can agree on a single language? Do they differ substantially?

[franciscoBSalgueiro]

It's the same language, so any portuguese speaking person would be able to read both. That being said, you can definitely tell one was written by a Brazilian and another by a Portuguese. I've seen some apps have both a pt_PT and pt_BR translation, but if you only want to have one, I think any of them would work.

[GyulyVGC]

If standard Portuguese is also comprehensible by Brazilians, I'd prefer to keep only one.
I kindly ask to @vrmiguel to review this PT translation and let me know if some term is not clear.
If something is not clear, may you find a version that suits both?
Thanks in advance guys!

[GyulyVGC]

Since #136 has been closed, I'll proceed merging this PR!

[GyulyVGC]

@all-contributors please add @franciscoBSalgueiro for translation

[allcontributors]

@GyulyVGC

I've put up a pull request to add @franciscoBSalgueiro! 🎉