Allow homepage links to open in new tab

A change was recently made to allow head and footer links to open in a new tab, rather than overriding the current page. However, this does not apply to the logo in the header, or to the Talis Aspire logo in the footer. We would like the same functionality to apply to these links also, so that people clicking on these logos are not taken away from the reading list page they are on, but are able to follow links to our University website from our logo, and to information about Talis Aspire from the Aspire logo.