Added missing grid make-column mixins and fixed some inconsistencies

make-column() was still been use to generate "medium size" columns (col-sm), while make-small-column was creating the default columns (col).
I also changed @grid-float-breakpoint to @screen-small, as it was used in make-row() and I think it makes more sense here than the other.
Make visibility utility classes responsive when used as LESS mixins
Removed Glyphicons mention from carousel.less
Changed "Standard pagination" to "Default pagination"
Update components.html

Keeping bs-examples consistent with code provided.
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
set img-circle class in percents
getting-started docs: rephrase to avoid "helpful...help"
Fixes #9260
Use protocol-relative URL in example
fixes #9111
Merge branch '3.0.0-wip' of github.com:twbs/bootstrap into 3.0.0-wip
fixes #9222
Merge pull request #9230 from ggam/patch-14

Changed "Standard pagination" to "Default pagination"