There are some issues in the brazilian portuguese translation:
```
less_than : "meno que"
```
the word "meno" doesn't exist in the language, the correct translation is "menos"
```
minute_read : "minuto(s) de leitura"
```
once we can one or more minutes of reading, the plural of the word "minuto" is optional, so we can use "(s)" after the word "minuto" to reflect this
```
related_label : "Talvez você goste também"
```
this change is for better reading, the previous translation is not good
I changed the capitalization of the subsequent words for lowercase to have default capitalization in all translations.
* Add YIQ Color Contrast mixin
* Remove text underline from `.btn` links
* Move YIQ variables
* Simplify button classes using YIQ color contrast mixin
- DRY up button CSS using Sass list and YIQ color contrast mixin.
- Move `color` and `background-color` to new `btn--primary` class instead of assinging on the default class. Removes the need to override them.
* Add `.btn--primary` to buttons that just had `.btn`
* Apply changes to `/docs`
* Add `.btn--primary` class
* Update CHANGELOG and history
* Add sample form
* Abstract colors away into Sass variables for easier themeing
* Add "dark" skin
* Replace hardcoded color with SCSS variable
* Invert Font Awesome icons' colors in author sidebar and footer
* Add Sass changes to `/docs`
* Use primary button type instead of inverse
* Add missing `!default` on `$muted-text-color`
* Add `contrast` and `sunrise` skin colors
* Add `dirt` skin color
* Add `air` skin color option
* Add `mint` skin color
* Add `btn--primary` class to Submit Comment button
* Set skin to `default`
* Document skin color options
* Add note about skin SCSS import
Close#1208
