Markup: Tweaked markup to better support screen readers

* Moved role="banner" to header element and added role="contentinfo" to footer element (based on http://blog.paciellogroup.com/2013/02/using-wai-aria-landmarks-2013/)
* Moved brand outside of a section (doesn't need section) and moved to the start of the header element (to resolve NVDA bug where it doesn't like a sectioning element being the first child element)
* Shortened multiple ids
* Removed some nesting to simplify the structure
* Grouped logo and site title into one link
* Applied i18n properties to more text (note  "Could not find property 'i18n'" error)
* Added site info text to i18n file