WIP: Bootstrap 3 (SASS)

**Reference**

https://github.com/twbs/bootstrap/pull/6342 3.0.0-wip Pull Request


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**update 08/20** This PR should have all changes including this commit https://github.com/twbs/bootstrap/commit/e8a1df5f060bf7e6631554648e0abde150aedbe _v.3.0.0 tag_

Let's do the last steps until the final release together. To ship this translation as fast as possible when bootstrap releases the final 3.0.0