Add Brazilian Portuguese translation

[fandangos]

About pull request

• This pull request adds Brazilian Portuguese translation as an option to the theme.

What's changed to accomplish [problem / feature] described in issue

This pull request doesn't change any previews code, except adding pt (portuguese) as an option to the main.conf file.
All the translation is nested in pt folder.
I have not translated the William Shakespeare quotes and other examples because those will end up being replaced by other users when using this theme, so I left those in place.

I also translated the README file and named it _README-pt.md (as the same as the Japanese one) and this can be added to the main project page by the main author of the theme. Because this is the author's choice, I have not added a link to the brazilian portuguese README.md file since those are linked directly to the author's of this theme github page.

Please, considere this as a gratitude for your work since I'm using your jekyll theme on my personal blog since yesterday (https://fandangos.github.io) but with only English and Portuguese language options as I don't speak Japanese.

[MrGreensWorkshop]

I can't tell you how I feel right now. I'm so happy. Please give me a little bit time to review.

[fandangos]

I forgot to translate 2 titles in the README, I'm sorry for that.
I've added a new commit and now it should be fully translated.

[MrGreensWorkshop]

Thanks to you, when I was checking the PR, I found a bug, #120 will fix your website month translation.
It is not related to this bug but, there are small things needs to change in this PR. Still checking.

[MrGreensWorkshop]

I make some changes, Could you please take a look at this commit 44c1a36 ?
I also add your name into readme files. Since I used Google translation please check.
I also changed translation for cookies, it's taken from googles page. I think its better to use them for each language. Overall please let me know what you think. Thank you again.

[MrGreensWorkshop]

Marked pages are good to go.

[fandangos]

I made some small changes to improve the translation.
In portuguese, you can use some words in English and those will be left in the phrase like the original.
If you translate Theme to Tema, it would be spoken before the title of the theme: Tema Mr. Green.
That's why I changed it.

Everything looks really good and I really appreciate the credits.
I'll write about this colaboration on my blog that is powered by Mr Green :))

[MrGreensWorkshop]

Everything is look good. Forgive me for my poor translations. I will update demo page too. I appreciate your time. Thank you.

[MrGreensWorkshop]

well all done.