Firefox inner focus fix

Firefox adds 2px padding/border to a button element. when you have a
.button and a button element next to each other this shows. (button is
2px taller). resetting -moz-focus-inner fixes this
Update _settings.scss

add variable missing
removes empty commands and added new missing command
adds SCSS: how it w works section
removes empty commands and added new missing command
rechanging layout and adding new content
Typos in _settings.scss

Only some typos…
Update _buttons.scss

Fixes breaking change in #5439
Add -webkit-border-radius: 0px; for corners

Didn't like the rounded corners WebKit adds to Form Inputs so added -webkit-border-radius: 0px; where I thought it should go to remove them. 

Before: http://c.rwh.im/image/3F0U0w2L1Y0g
After: http://c.rwh.im/image/1p3w3d2C2239
Merge pull request #5368 from hughker/patch-1

Fix for WebKit rounded form input corners
Merge pull request #5367 from avr/patch-1

Update _buttons.scss
Merge pull request #5364 from Shiva127/master

Typos in _settings.scss
Merge pull request #5305 from andersonaguiar/patch-1

Update _settings.scss
Merge pull request #5211 from pinoniq/master

Firefox inner focus fix
Update _settings.scss for additional Side Nav variables
do not print unnecessary comments
do not print `.icon-bar` if `$include-html-form-classes` is `false`
Added Label in Warning-Color
Merge pull request #5376 from wolfgang-demeter/warning-label

Added Label in $warning-color
Merge pull request #5374 from Grawl/master

remove unneeded comments and selectors from output