Move examples out of the main repo to twbs/bootstrap-examples

While examples are phenomenally useful and awesome for folks getting
started with Bootstrap, they don't really shine as well being buried in
the main docs. Moreover, having anything that's not core HTML, CSS, JS,
or documentation in the main repo seems to just get in the way.
Therefore, examples gets its own repo.

Specifically, we're doing the following:

* Deletes all example screenshots
* Deletes example layout
* Deletes example files
* Updates Getting Started docs to include only the template and a link
to the new examples project

All the examples and their history will be preserved in the switch.
Docs: create new callout classes
Update mixins.less

Add a the function .make-small-column. See also http://stackoverflow.com/a/17308128/1596547
Adjust info callout, add callouts to docs

* Adjust the background-color of bs-callout-info to match danger and
warning in tone
* Convert all the callouts
* Change some callouts to info/warning
* Add new callout
Tooltip: apply position class before positioning
Prevent the font shorthand from getting compiled as division
simplify tables.less
Fix responsive utilities for table elements

This change prevents situations where specificity causes some rules to
be overridden by the ones intended for mobile.
* Added mixin `responsive-invisibility()`
* Swapped out `display: none !important;` for new mixin
Make more components mixin-friendly
Merge branch '3.0.0-wip' of github.com:twitter/bootstrap into 3.0.0-wip
fixes #7367: slightly larger carousel indicators
fixes #8068: add .help-block to form field state mixin
Merge pull request #8352 from liuyl/simplifytable

simplify tables.less
fixes #8345: use inline-block on .img-responsive
Merge pull request #8348 from Rowno/compiled-font-shorthand

Prevent the font shorthand from getting compiled as division
Fixes #8350: unfuck Chrome number input element cursor /cc @cvrebert @eintnohick
Merge branch '3.0.0-wip' of github.com:twitter/bootstrap into 3.0.0-wip
Merge branch '3.0.0-responsive-tables' of https://github.com/juthilo/bootstrap-wip into juthilo-3.0.0-responsive-tables

Conflicts:
	less/mixins.less
comma for the guardian angel /cc @cvrebert
refactor tables.less to use nesting more