Brazilian Portuguese adds and corrections

Added some Brazilian Portuguese missing strings and corrected some
others.
Some terms used in PyroCMS (as streams, widgets, slug) were left in
English.
String language corrected to context.
File was ANSI encoded. Now it's UTF-8 without BOM.

The file was using the wrong encoding, causing strange characters to
show.
Reverting back changes to 2 files

Despite having minimal changes, these files are displaying a full-file
diff. Their changes were reverted back while we try to discover what
happened.
Revert bach change to 1 file

system/cms/modules/maintenance/details.php is marked as an all diff too.
Reverted it back to before the changes.
Fixed an string error
Merge pull request #2918 from RodrigoBalest/2.2/develop

Brazilian Portuguese strings additions and corrections