Correct "Aligninment" -> "Alignment" typo.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Removing whitespaces
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
Merge branch 'master' of https://github.com/twbs/bootstrap