Navbar refactor

* Now responsive by default (fits better with mobile-first approach)
* Requires `.nav-header` to group `.navbar-brand` and `.navbar-toggle`
for proper mobile display.
* Changed `.nav-collapse` to `.navbar-collapse`
* Simplified examples in docs
Merge branch '3.0.0-wip' into bs3_navbar_overhaul

Conflicts:
	components.html
	dist/css/bootstrap.min.css
invert dropdown styles in navbar for inverse variation
Drop the accordion for the panel

* Deletes the accordion.less file
* Extends the panel to be collapsible with our JS plugin
* Supports panel color variations
copy
Added pagination-size mixin
Fixed errors
derp
Added input-size mixin
enable button groups in vertical button groups
Merge pull request #9424 from twbs/bs3_btn_groups

BS3: `.btn-group`s for your `.btn-group`s
Merge pull request #9421 from ggam/input-size

Added input-size mixin
Merge pull request #9410 from ggam/pagination-size

Added pagination-size mixin
Merge branch '3.0.0-wip' into bs3_drop_accordion_for_panel

Conflicts:
	dist/css/bootstrap.min.css
Merge pull request #9404 from twbs/bs3_drop_accordion_for_panel

BS3: Drop the accordion for the panel (fixes #8648)
fixes #9425: focused input in docs gets actual focus styles
Merge branch '3.0.0-wip' of github.com:twbs/bootstrap into 3.0.0-wip
fix mixin code example
Merge pull request #9427 from saiwang/fix-example-snippet

fix mixin code example
fixes #9431: specify font-size in dropdown menus to avoid inheritance issues