Update less/carousel.less

lessified .carousel-caption
Merge pull request #6750 from nextgenthemes/3.0.0-wip

Update less/carousel.less
Merge branch '3.0.0-wip' of https://github.com/GeoffYoung/bootstrap into 3.0.0-wip

* '3.0.0-wip' of https://github.com/GeoffYoung/bootstrap:
  Set button text color and caret color in variables