add loading class for mdo to style on customizer
Merge branch '3.0.0-wip' of github.com:twbs/bootstrap into 3.0.0-wip
fixes #6159
panels
Merge pull request #9271 from liuyl/panels

refactor panels.less
navbar.less
Merge pull request #9273 from liuyl/navbars

navbar.less
Merge branch '3.0.0-wip' of https://github.com/twbs/bootstrap into develop