quick fix for docs mention
Correct "Aligninment" -> "Alignment" typo.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Removing whitespaces
Add role="toolbar" to elements with .btn-toolbar.
Merge pull request #9918 from lamby/master

Correct "Aligninment" -> "Alignment" typo.
Merge pull request #9930 from tagliala/whitespaces-fix

Removed trailing whitespaces in responsive-utilities.less
fix #9924
fix #9917
CONTRIBUTING: reflect move away from *-wip branch style of development

Per http://blog.getbootstrap.com/2012/12/10/bootstrap-3-plans/ :
> * Drop the `*-wip` branch style of development.
point release download link to an actual release instead of `master`
links to a release instead of master, so rephrase description accordingly
master branch is no longer stationary, so don't imply otherwise
fix #9915
update copyright year
add variables for heading font sizes; fixes #9921
regenerate customizer's raw-files.js
add header font size vars to customizer page
Apply @color argument to striped gradient

The @color argument is currently not being used for the striped gradient.
Remove progress bar striped @color parameters; use default transparent white.

* If the @color parameter is not removed, the stripes are the same color as the element background color. In this case, the stripes do not appear.
rename @screen-XX to @screen-XX-min for clarity+unambiguity