Making Uni Logo SVGs more accessible 

Added aria-labels, titles and descriptions to the SVGs of University's logo which appears in the header, footer and sitemap sections of all pages.

[Sitepoint tips](http://www.sitepoint.com/tips-accessible-svg/), [Stackoverflow suggestions](http://stackoverflow.com/questions/4697100/accessibility-recommended-alt-text-convention-for-svg-and-mathml).

Fixes #126