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
getting-started docs: rephrase to avoid "helpful...help"
Fixes #9260
Use protocol-relative URL in example