Fixes issue #505: Module links in webadmin should use _blank.

[Wikipedia Icon External Link](http://commons.wikimedia.org/wiki/File:Icon_External_Link.png) is being used as an icon for the external link.
No we can't, but relative URLs in CSS files are relative to the CSS file itself, so something like '../skinfiles/foo' could work: http://stackoverflow.com/questions/2161377/is-the-html-base-tag-also-honored-by-scripting-and-css