* Add custom header support
* header.php: use `get_stylesheet_uri()` to load stylesheet, props Mamaduka
* Add full-width template, including adding relevant body_class value as a CSS hook
* Hide sidebar on all views if no active widgets exist
* Fix site title output (was missing site title)
* Remove "featured" title for sticky posts
* Add content template files for aside, image, link, and quote post formats
* Indent content-single.php to match content.php
* Remove sample JPG since Twenty Twelve ships with no default header images
... and style updates, props drewstrojny
* Better footer styles
* Styling for full-width layouts
* Add basic styles for archive views
* Refine post header/footer styles a bit
git-svn-id: https://develop.svn.wordpress.org/trunk@19915 602fd350-edb4-49c9-b593-d223f7449a82
