Language Support - Add translations for Brazilian Portuguese

[gmcrocetti]

Problem

Lack of Brazilian-Portuguese translation.

Solution

Pretty straightforward. Add translation files for pt_BR.

Commandments

• Write PEP8 compliant code.
• Cover it with tests.
• Update CHANGES.rst file to describe the changes, and quote according issue with GH-<issue_number>.
• Pay attention to backward compatibility, or if it breaks it, explain why.
• Update documentation (if relevant).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.01%. Comparing base (99458d6) to head (f39c975).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #578   +/-   ##
=======================================
  Coverage   95.01%   95.01%           
=======================================
  Files           6        6           
  Lines         803      803           
=======================================
  Hits          763      763           
  Misses         40       40           

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[foarsitter]

Thanks @gmcrocetti