refactor tables.less to use nesting more

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

Prevent the font shorthand from getting compiled as division

simplify tables.less

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

Docs: Fix broken links to navbar component in examples pages

Remove references to fonts

reset left padding for .media-list, .pagination and .pager

* Any mentions of .btn-mini
* Old docs page that somehow found it's way back

removing bootstrap-fonts rule in Makefile for bootstrap rule

`img`s are no longer responsive by default. Instead, use
`.img-responsive` as a class or mixin. Existing `.thumbnail > img` and
`.img-thumbnail` classes now make use of this as a mixin as well.

Fixes #7213 Collapse plugin does not correctly set the "collapsed" class.

fixes #7961 a bit: adds css for extra tooltip placement options. /cc @fat you just need dat js prolly

remove submenus. for more context: http://www.youtube.com/watch?v=ggWyUEuGcWY&feature=youtu.be&t=48s

Fixed mixin btn-pseudo-state background for [disabled] buttons