(bug 18338) WAI-ARIA landmark roles in most used skins

(bug 18338) WAI-ARIA landmark roles in most used skins

Add of most commons langmark roles (main, banner,
navigation, contentinfo and search) to vector, monobook,
cologneBlue and modern skins.
ARIA specification: http://www.w3.org/TR/wai-aria/

WAI-ARIA (Web Accessibility Initiative - Accessible Rich
Internet Applications) is a specification published by
the W3C that specifies, between other things,
a set of values for the "role" attribute in order to
increase the accessibility of web pages.
ARIA is now suported by most of the reading systems.

Change-Id: I470acb8bda50e4f43ad53624dd268fc40cc2fcfd