Add callout to docs: 3rd-party libs not supported
Add callout to docs: LESS compiler support
Add a link to the mailing list for JS help
refactor responsive-utilities slightly
Add IDs, adjust text
fix "Data attributes" link in JS docs sidenav

`#js-data-attributes` => `#js-data-attrs`
fix ID of Normalize heading in docs so that the sidenav can find it
Recess welcome
Merge pull request #8294 from cvrebert/patch-2

fix ID of Normalize heading in docs so that the sidenav can find it
Merge pull request #8291 from cvrebert/refactor

refactor responsive-utilities slightly
Move mixin to mixins.less
Merge pull request #8292 from cvrebert/patch-1

fix "Data attributes" link in JS docs sidenav
Merge pull request #8290 from juthilo/3.0.0-docs-nothird

Add new callouts to docs
Merge branch '3.0.0-wip' of github.com:twitter/bootstrap into 3.0.0-wip