Updates for 2.6.2 and 2.9.1 releases
Update copyright year to 2014 in page footer
Add and use content of http://download.banshee.fm/documents/
Add and use 1click-install-button.png from http://download.banshee.fm/
css: Fix alignement of table headers in download page
Add Lightbox for image overlay in release pages
Add and use images from http://download.banshee.fm/shots/

Add the various screenshots used in the release pages to the website,
instead of having them on a separate server. Modify the image references
to /images/shots/

Also clean up the archives posts that are modified, fixing various
layout issues in the process.