<link> URLs are tracked and shouldn't be

[larssandergreen]

Related to #43, if you use <link href=URL>, for example to load a webfont, that URL is converted to a tracked URL. Presumably it shouldn't be as this messes up the clickthrough statistics. I would think any URL in a link tag should be ignored and only URLs inside a tags should be tracked, though obviously that's a little more complicated to do.