Fixed nested tab elements li activation

Added closest li instead of direct parent so that you can nest multiple elements within tabs, such as button groups
Dropdown menu in justified button-group

It seems that dropdown-menu in justified button-group appears at the far
left of the group. Check the problem in [Bootstrap
site](http://getbootstrap.com/components/#btn-groups-justified).
cleanup
fixes #12211: Scrollspy: Navs in different tabs can interfere with each othe
Merge pull request #13576 from twbs/fat-12211

fixes #12211: Scrollspy: Navs in different tabs can interfere with each ...
nuke rtl
Merge branch 'master' of github.com:twbs/bootstrap
grunt
nuke the rtl docs
nuke the rtl example
remove the comment
Merge pull request #13369 from armikbd/bootstrap-itsme

Dropdown menu in justified button-group
grunt dist
Merge pull request #13191 from AshleyDawson/master

Fixed nested tab elements li activation
versions
grunt dist
Merge pull request #13578 from twbs/fat-versions

versions
grunt for raw js
Merge branch 'master' of github.com:twbs/bootstrap
grunt